Chunky Monkey Oatmeal Cookie Skillet

Featured in: Sweet & Calm Treats

This Chunky Monkey Oatmeal Skillet combines everything you love about the classic smoothie flavors—ripe bananas, rich semisweet chocolate chips, and crunchy walnuts—into one warm, comforting baked dessert. The oatmeal-based dough creates a hearty texture that's perfectly suited for skillet baking, resulting in golden edges with a slightly soft center. Best served warm from the oven, this shareable treat feeds eight people and comes together in under 40 minutes. The cast-iron method creates those coveted crispy edges while keeping the interior tender and moist. Top with vanilla ice cream for the ultimate finishing touch.

Updated on Mon, 09 Feb 2026 08:37:00 GMT
Golden-baked Chunky Monkey Oatmeal Cookie Skillet emerges from the oven, loaded with melted chocolate chips, walnuts, and ripe banana pieces. Save
Golden-baked Chunky Monkey Oatmeal Cookie Skillet emerges from the oven, loaded with melted chocolate chips, walnuts, and ripe banana pieces. | moonthyme.com

My sister called me one Tuesday afternoon asking if I could bring dessert to her place that weekend, and honestly, I was stuck. Then I caught sight of a bunch of bananas on my counter that were almost past their prime, and something clicked—why not turn them into a skillet cookie? The result was this chunky, warm thing that tastes like someone liquified a Chunky Monkey smoothie and baked it into golden, shareable form. When I pulled it from the oven and brought it still-warm to her apartment, people literally gathered around like I'd done something revolutionary. It wasn't fancy, but it felt special in the way only warm, feed-your-people food can be.

There's a memory tucked into this recipe of a random Friday when my neighbor knocked with fresh walnuts from her tree and asked if I could use them. I didn't have a plan, but I mixed them into this skillet cookie dough, and when the warm smell drifted through my house, she ended up staying for coffee and we split it right there at my kitchen counter. Sometimes the best dishes happen when you say yes to whatever's in front of you.

Ingredients

  • Old-fashioned rolled oats (1 1/2 cups): These create texture and substance without making the cookie feel overly cakey—they're the backbone that keeps everything together and gives you those satisfying chewy bits.
  • All-purpose flour (1 cup): Use the spoon-and-level method rather than scooping directly into the bag; it makes a real difference in the final texture.
  • Unsalted butter, melted (1/2 cup): Melting it first helps everything blend smoothly and distributes the richness evenly throughout the dough.
  • Ripe mashed bananas (about 1 cup): They need to be soft enough to mash easily with a fork—this is where moisture and natural sweetness come from, so don't skip this.
  • Brown sugar (1/2 cup) and granulated sugar (1/4 cup): The combination of both creates depth; brown sugar adds moisture and molasses notes while granulated sugar helps with structure.
  • Baking soda and salt: These work together to control the rise and balance sweetness—don't be tempted to skip either one.
  • Semisweet chocolate chips (1/2 cup): These melt slightly into the warm dough without disappearing, creating pockets of richness throughout.
  • Chopped walnuts (1/2 cup): Toast them lightly before folding in if you want deeper, more pronounced nutty flavor—it's a small step that makes a noticeable difference.
  • Shredded coconut (1/4 cup, optional): This adds tropical notes that play beautifully with the banana, but it's truly optional depending on your preference.

Instructions

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Get your skillet ready:
Preheat the oven to 350°F and give your 10-inch cast-iron skillet a light coating of butter or nonstick spray. Cast iron holds heat beautifully and gives you those slightly caramelized edges that make this cookie special.
Combine the dry ingredients:
Whisk together the oats, flour, baking soda, salt, and cinnamon in a large bowl until everything is evenly distributed. This step prevents clumps of baking soda from creating weird bitter pockets later.
Build the wet mixture:
In another bowl, whisk the melted butter with both sugars until the mixture looks smooth and well combined. Add the egg and vanilla, whisking until you have no streaks, then fold in the mashed bananas gently—you want them incorporated but not overmixed.
Bring wet and dry together:
Pour the wet mixture into the dry ingredients and mix just until you don't see any flour streaks. Overmixing develops gluten and makes the cookie tough, which defeats the purpose.
Fold in the good stuff:
Gently fold in the chocolate chips, walnuts, and coconut if using, being careful not to crush anything. This is where you can pause and taste a tiny bit of dough if you want to—no judgment here.
Into the skillet:
Pour the dough into your prepared skillet and spread it to the edges as evenly as you can. The dough will be thick and a bit sticky, but that's exactly right.
Bake to golden perfection:
Bake for 20 to 24 minutes, watching for the edges to set and the top to turn golden brown while the very center stays slightly soft. This creates the perfect texture—crispy edges giving way to a tender, almost fudgy middle.
Rest and serve:
Let the skillet cool for about 10 minutes so you don't burn your mouth, then cut it into wedges and serve straight from the pan. A scoop of vanilla ice cream on top is entirely optional but never unwelcome.
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A warm slice of Chunky Monkey Oatmeal Cookie Skillet is scooped onto a plate, revealing a gooey center perfect for serving with vanilla ice cream. Save
A warm slice of Chunky Monkey Oatmeal Cookie Skillet is scooped onto a plate, revealing a gooey center perfect for serving with vanilla ice cream. | moonthyme.com

I think about a moment last summer when my nephew asked me to make this for his birthday dinner because he'd had it once and apparently dreamed about it. Watching him cut into it and seeing his face when he realized it was warm and still soft in the middle—that's when I understood this recipe was more than just ingredients and technique. It became something people actually wanted.

Why Cast Iron Matters Here

There's something about cast iron that changes how this cookie bakes. The even heat distribution means you get golden edges without burning the bottom, and the pan itself becomes part of the presentation—there's something inherently warm and inviting about passing around a skillet instead of a plate. If you don't have cast iron, a 10-inch round cake pan works fine, though you'll lose a tiny bit of that rustic appeal and maybe 1 to 2 minutes of baking time since cake pans conduct heat differently.

Making This Your Own

The beauty of this cookie is that it's flexible without losing its identity. I've made versions with peanut butter chips instead of chocolate, swapped the walnuts for pecans when that's what was in the pantry, and even added a teaspoon of instant coffee powder to deepen the chocolate notes. One time I pressed brown sugar turbinado crystals on top before baking for a subtle crunch. The bones of the recipe—banana, oats, and warm spices—stay consistent, but you get to play around with the toppings and mix-ins based on what feels right.

Storage and Reheating

This cookie tastes best eaten warm or at room temperature the same day you make it, but it keeps well covered at room temperature for up to two days. To reheat, place the skillet back in a 300°F oven for about 5 minutes until it's warm through without drying out, or wrap individual slices in foil and warm them gently. Honestly, I've also eaten cold slices straight from the fridge and they're still pretty good, just in a different way—more like cake than cookie.

  • If you're baking this ahead for a gathering, let it cool completely, cover it loosely, and reheat it gently just before serving.
  • Leftover slices reheat beautifully in the microwave for 20 to 30 seconds if you're in a rush and don't mind a slightly softer texture.
  • This recipe doesn't freeze particularly well because of the banana and the cast-iron presentation, so make it fresh when you need it most.
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Freshly baked Chunky Monkey Oatmeal Cookie Skillet sits in a cast-iron pan, showcasing a golden crust with chunks of banana, walnuts, and chocolate. Save
Freshly baked Chunky Monkey Oatmeal Cookie Skillet sits in a cast-iron pan, showcasing a golden crust with chunks of banana, walnuts, and chocolate. | moonthyme.com

This skillet cookie has become the dessert I make when I want people to feel cared for without making a big production of it. It's honest food that tastes like home.

Recipe FAQ

Can I make this skillet cookie ahead of time?

Yes, you can prepare the dough up to 24 hours in advance and store it covered in the refrigerator. Bake when ready to serve, adding 2-3 minutes to the baking time if baking from cold. Leftovers reheat beautifully in a 350°F oven for 5-10 minutes.

What if I don't have a cast-iron skillet?

You can use any 10-inch oven-safe skillet, cake pan, or square baking dish. Adjust baking time as needed—shallow pans may bake faster, while deeper dishes require a few extra minutes. The edges should be golden and center set but slightly soft.

Can I use quick oats instead of old-fashioned rolled oats?

Old-fashioned rolled oats provide the best texture, but quick oats will work in a pinch. The final product may be slightly softer and less chewy. Steel-cut oats are not recommended as they won't soften properly during baking.

How do I know when it's done baking?

The skillet is ready when the top is golden brown and edges are set, but the center still has a slight jiggle when you gently shake the pan. It will continue firming up as it cools during the 10-minute resting period. A toothpick inserted in the center should come out with moist crumbs, not wet batter.

Can I freeze this skillet cookie?

Absolutely! Bake and cool completely, then wrap tightly in plastic wrap and foil. Freeze for up to 3 months. Thaw overnight in the refrigerator, then reheat in a 350°F oven for 10-15 minutes until warmed through. You can also freeze the unbaked dough and bake fresh.

What other mix-ins can I use?

Feel free to customize with your favorite additions. Try peanut butter or butterscotch chips instead of chocolate, pecans or almonds instead of walnuts, or add dried fruit like raisins or chopped dates. Keep the total mix-in quantity around 1 ¼ cups for best results.

Chunky Monkey Oatmeal Cookie Skillet

Warm, shareable skillet dessert with banana, chocolate chips, and walnuts baked in a cast-iron pan to golden perfection.

Prep Time
15 min
Time to Cook
22 min
Total Duration
37 min
Created by Lydia Brooks


Skill Level Easy

Cuisine American

Portions 8 Serving Size

Diet Info Vegetarian Friendly

What You'll Need

Dry Ingredients

01 1 1/2 cups old-fashioned rolled oats
02 1 cup all-purpose flour
03 1/2 teaspoon baking soda
04 1/2 teaspoon salt
05 1/2 teaspoon ground cinnamon

Wet Ingredients

01 1/2 cup unsalted butter, melted and slightly cooled
02 1/2 cup light brown sugar, packed
03 1/4 cup granulated sugar
04 1 large egg
05 2 teaspoons vanilla extract
06 2 medium ripe bananas, mashed

Mix-Ins

01 1/2 cup semisweet chocolate chips
02 1/2 cup chopped walnuts
03 1/4 cup unsweetened shredded coconut, optional

How to Make It

Step 01

Prepare Skillet and Preheat Oven: Preheat oven to 350°F. Lightly grease a 10-inch cast-iron skillet with butter or nonstick spray.

Step 02

Combine Dry Ingredients: In a large bowl, whisk together oats, flour, baking soda, salt, and cinnamon.

Step 03

Mix Wet Ingredients: In a separate bowl, combine melted butter, brown sugar, and granulated sugar. Whisk until smooth.

Step 04

Incorporate Egg and Banana: Add egg and vanilla extract to the wet mixture and whisk well. Stir in mashed bananas until fully combined.

Step 05

Combine Wet and Dry Mixtures: Pour wet mixture into dry ingredients and mix until just incorporated.

Step 06

Fold in Mix-Ins: Gently fold in chocolate chips, walnuts, and coconut if using.

Step 07

Transfer to Skillet: Spread dough evenly into the prepared cast-iron skillet.

Step 08

Bake: Bake for 20 to 24 minutes, or until the top is golden and the edges are set but the center remains slightly soft.

Step 09

Cool and Serve: Let cool for 10 minutes before serving warm. Serve slices directly from the skillet, optionally topped with ice cream.

Tools Needed

  • 10-inch cast-iron skillet
  • Mixing bowls
  • Whisk
  • Spatula
  • Measuring cups and spoons

Allergen Details

Review every ingredient for allergens and ask a medical professional when unsure.
  • Contains wheat (gluten)
  • Contains eggs
  • Contains milk (butter and chocolate chips)
  • Contains tree nuts (walnuts)
  • Coconut may be considered a tree nut allergen

Nutrition Details (each serving)

These details are for reference only, and shouldn't replace healthcare advice.
  • Energy: 320
  • Fats: 16 g
  • Carbohydrates: 41 g
  • Proteins: 5 g