Rainbow Fudge Cookie Bars

Chewy, fudgy chocolate chip cookie bars topped with chocolate fudge and rainbow M&M’S. Only 4 ingredients needed to make Rainbow Fudge Cookie Bars!

This recipe was originally published in September 2014. I updated the recipe notes and added new photos in April 2026.

Aimee’s Recipe Notes

Sometimes you don’t want to run all over the store tracking down the ingredients you need to make a delicious dessert.

When you don’t have the time or the energy for a complicated cookie bar recipe, these easy four ingredient fudge cookie bars are the solution! Not to be confused with these 3 ingredient peanut butter cookies!

Starting with a roll of cookie dough, you can make a layered cookie bar that’s full of chocolate and topped with a crunchy layer of M&Ms.

The colorful candies add a rainbow splash to these cookie bars that’s just right for a birthday party!

xo,

Only Four Ingredients

Here’s all you need to make fudge cookie bars:

• Cookie dough – Use a 30 ounce package of your favorite chilled chocolate chip cookie dough. Or use my chocolate chip cookie bar recipe!
• Sweetened condensed milk– You’ll need one can for the topping.
• Chocolate chips – I used milk chocolate, but semi sweet would work too for a smooth chocolate flavor.
• Mini M&Ms – Use the package of baking M&Ms for best results or swap full sized M&Ms if preferred.

How to Make Rainbow Cookie Bars

Bake the cookie bars.

• You’ll line a cookie sheet (15x10x1-inch) with parchment paper. Press the dough lightly into the bottom (it’s okay if it doesn’t go all the way to the edges).
• Bake until lightly browned (don’t overbake the dough).

Make the Topping.

• You can make the fudge layer for these bars using your microwave! I heat the condensed milk and the chocolate morsels together in the microwave for 30 second increments, stirring smooth between intervals. This will take about 1-2 minutes.
• Pour the fudge layer over a baked layer of cookie dough, top with M&Ms and let the bars chill in the fridge until the fudge layer is set. This takes at least 2 hours but you could also make them in advance to let the fudge chill over night.

More Birthday Desserts

• Some version of an Ice Cream Cake tends to be the “treat of choice” for several of my children each year!
• Mint Chocolate Chip Cake isa show stopper of a cake that tastes like my favorite ice cream!
• Dark Chocolate Cake with Vanilla frosting is the world’s most perfect chocolate cake recipe.
• Birthday Cake Biscotti is the perfect way to send your favorite person a birthday wish. Bake a batch of biscotti and ship it! It keeps well when shipping!
• This Rainbow Buttercream board is a fun dessert idea for holidays and parties.
• My classic yellow cake with chocolate frosting is a great way to celebrate the big day!

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Rainbow Fudge Cookie Bars Recipe

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By: Aimee Shugarman

These Rainbow Fudge Cookie Bars are the perfect birthday treat. Chocolate chip cookie dough topped with fudge and M&M's candies!

Prep Time: 10 minutes minutes

Cook Time: 15 minutes minutes

Chill Time: 2 hours hours

Total Time: 2 hours hours 25 minutes minutes

Servings: 48 bars

Ingredients 

1x2x3x

• ▢ 1 refrigerated chocolate chip cookie dough, 30 ounce
• ▢ 14 ounce sweetened condensed milk
• ▢ 11 ounce package milk chocolate morsels
• ▢ 12 ounce package baking M&M's, or mini M&M's

Instructions 

• Press cookie dough into a parchment paper lined 15x10x1-inch baking sheet. Bake in a 350 degree oven for 15 minutes. Remove and cool slightly.
• In a microwave safe bowl, combine sweetened condensed milk with chocolate morsels. Heat for 30 seconds, stir, and heat an additional 30 seconds. Stir until smooth and creamy. Spread evenly over baked cookie bars.
• Sprinkle immediately with m&m minis. You can use regular sized candies if you prefer.
• Refrigerate until fudge layer sets up (about 2 hours, or overnight). Store in airtight container. ENJOY

Notes

• Use homemade chocolate chip cookie bars instead of store bought if you prefer.
• Want thicker bars? Use a 13×9 instead.
• Store: keep cooled cookie bars in an airtight container at room temperature for up to one week. Or freeze for up to 3 months.
• See blog post for step by step photos and more!

Nutrition

Serving: 1cookie, Calories: 27kcal, Carbohydrates: 4g, Protein: 1g, Fat: 1g, Saturated Fat: 0.5g, Polyunsaturated Fat: 0.03g, Monounsaturated Fat: 0.2g, Cholesterol: 3mg, Sodium: 11mg, Potassium: 31mg, Sugar: 4g, Vitamin A: 22IU, Vitamin C: 0.2mg, Calcium: 23mg, Iron: 0.02mg

Course: Cookies

Cuisine: American

Did you make this recipe?Mention @shugarysweets or tag #shugarysweets!

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