Brown Butter Rice Cereal Marshmallow Cookies

These brown butter rice cereal marshmallow cookies are a cozy, nostalgic twist on two classic treats. Rich, nutty brown butter meets crisp rice cereal for an unexpectedly sophisticated crunch, while little pockets of mini marshmallow melt into soft, pillowy bites. The cookies are lightly browned on the edges and tender in the middle, with a toasty aroma that fills the kitchen as the butter caramelizes. They are perfect for casual cookie plates, bake sales, holiday trays, or an after-school treat with a cold glass of milk. If you love buttery cookie recipes with a playful texture contrast, this one pairs nicely with other comforting cookies like my buttery brown sugar cinnamon cookies. These are a great make-ahead cookie because you can freeze the dough balls and bake fresh cookies anytime.

Ingredients

1 cup unsalted butter, cut into 16 pieces — for browning; gives a deep, nutty flavor and silky mouthfeel.
2 and 1/4 cups all-purpose flour — provides structure and a tender crumb.
2 teaspoons cornstarch — keeps cookies soft and slightly delicate in texture.
1 teaspoon baking soda — helps the cookies spread and rise a bit.
1/2 teaspoon salt — balances sweetness; reduces to taste if using salted butter.
2 cups crispy rice cereal — adds crisp, light crunch throughout the cookie.
1 cup mini marshmallows — melt into sweet pockets that create chew and softness.
3/4 cup packed light or dark brown sugar — adds moisture and a caramel note; dark brown intensifies the flavor.
1/2 cup granulated sugar — helps with browning and a slight crisp edge.
1 large egg, at room temperature — binds the dough and adds tenderness.
1 large egg yolk, at room temperature — extra richness for a chewier center.
2 teaspoons pure vanilla extract — rounds and lifts all the flavors.
Optional: flaky sea salt, for topping — a sprinkle enhances the brown butter and balances sweetness, use if desired.

If you enjoy brown butter in cookies, you might also like this butter pecan cookie variation for a different nutty profile.

Step-by-Step Instructions

Brown the butter: Place the 1 cup of unsalted butter pieces in a light-colored skillet over medium heat. Stir constantly until the butter foams, then dark brown specks appear and it smells nutty. Watch closely so it does not burn. Remove from heat and set aside to cool slightly so it is warm, not hot, before combining with eggs.
Whisk dry ingredients: In a large bowl, whisk together 2 and 1/4 cups all-purpose flour, 2 teaspoons cornstarch, 1 teaspoon baking soda, and 1/2 teaspoon salt until evenly combined.
Fold in cereal and marshmallows: Add 2 cups crispy rice cereal and 1 cup mini marshmallows to the dry mixture. Fold gently so the cereal and marshmallows are distributed without crushing them.
Combine wet ingredients: In a separate bowl, whisk the cooled brown butter with 3/4 cup packed light or dark brown sugar, 1/2 cup granulated sugar, 1 large egg, 1 large egg yolk, and 2 teaspoons pure vanilla extract until smooth and homogenous. Tip: If the butter is too hot it can cook the egg, so ensure the mixture is only warm.
Make the dough: Pour the wet mixture into the dry ingredients and stir with a sturdy spoon until combined, forming a sticky dough. It will be thick and studded with cereal and marshmallows.
Form the cookies: Using a tablespoon or scoop, measure about 2 tablespoons of dough per cookie. Roll each portion into a ball and place on a baking sheet or tray. Freeze the dough balls for 1 hour. Freezing helps keep the cookies tall and gives a nice texture contrast between crisp exterior and soft center. For technique ideas, see this baker-style cookie guide for chilling tips.
Preheat oven: Preheat your oven to 350°F (177°C) and line baking sheets with parchment paper. Use an oven rack in the middle position for even baking.
Bake: Arrange the frozen dough balls on the prepared sheets, leaving 2 inches between each cookie. Bake for 14 to 15 minutes, until the edges are lightly browned and the centers look set but still soft.
Finish and cool: If using, sprinkle flaky sea salt on the warm cookies as soon as they come out of the oven. Allow the cookies to cool on the baking sheet for 10 minutes before transferring to a wire rack to cool completely.

Recipe Details

Prep Time: 1 hour 20 minutes (includes 1 hour freezing)
Cook Time: 14 to 15 minutes per batch
Total Time: 1 hour 35 minutes
Servings: Makes about 20 cookies (using 2 tablespoons dough per cookie)
Calories: Approximately 215 kcal per cookie

Tips, Storage & Variations

Tips
- Use a light-colored skillet to brown butter so you can see the color change clearly.
- Let the brown butter cool until just warm before whisking into eggs to avoid scrambling.
- Freeze dough balls on a tray first, then store them in a sealed container to keep their shape.
Storage
- Store baked cookies in an airtight container at room temperature for up to 3 days.
- Refrigerate for up to 1 week if you prefer a firmer cookie.
- Freeze baked cookies in a zip-top bag for up to 2 months. Thaw at room temperature.
- Dough balls can be frozen, tightly wrapped or in an airtight container, for up to 1 month. Bake from frozen, adding 1 to 2 minutes to the bake time.
Variations using ingredients in this recipe only
- Use dark brown sugar instead of light for a deeper molasses character.
- Increase mini marshmallows slightly for more gooey pockets in each bite.
- Skip the flaky sea salt if you want uniformly sweet cookies.
- Add an extra handful of cereal for a crisper, more cereal-forward texture.
  For a bright take on brown sugar in cookies, you may enjoy the technique in this brown sugar rhubarb cookie write up.

FAQ

How do I know when the butter is properly browned?
A: It will foam, then the milk solids will turn golden brown with a nutty aroma. Remove from heat right away to prevent burning.
Can I skip the freezing step?
A: You can, but freezing helps the cookies stay taller and creates a better chew to crunch ratio.
Will the marshmallows melt completely?
A: The mini marshmallows will soften and create sweet pockets, but some may retain small bits of chew for texture.
Can I use salted butter instead of unsalted?
A: Yes, but reduce or omit the additional 1/2 teaspoon of salt to avoid over-salting.
How should I bake if I freeze the dough balls longer than 1 hour?
A: Bake from frozen and add 1 to 2 minutes to the total bake time, watching for lightly browned edges.

Conclusion

I hope these brown butter rice cereal marshmallow cookies become a favorite in your cookie rotation. They balance nutty, caramel notes with marshmallow softness and a fun crunchy texture that both kids and adults will enjoy. If you want a marshmallow-forward inspiration, check this Marshmallow Crispy Cookies Costco copycat recipe for a related idea, or read this brown butter rice crispy treats piece for another take on browned butter with rice cereal. Share your results and any tweaks you try, and enjoy warm cookies with good company.