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Monster Mash Halloween Bars Recipe

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These monster mash Halloween bars are crazy simple to make, and loaded with fun Halloween colors. Whip up a batch of these double chocolate Halloween cookie bars with a homemade buttercream frosting.

This is a cute Halloween dessert that kids and adults can enjoy. The double chocolate cookie bars are so quick to whip up. A fun non-spooky treat for your Halloween bash.

stacked cookie bars on white plates on table

I am in love with this buttercream frosting recipe. It is the perfect frosting for these frosted cookie bars.

A cute dessert with rich chocolate cookie flavor, and sweet frosting, and colorful sprinkles.

Why You Will Love This Easy Halloween Dessert

  • Homemade double chocolate cookie batter
  • Homemade frosting
  • A fun Halloween food idea for kids – not spooky
  • Mix, bake, and serve
  • Freezer friendly

Ingredients You Will Need

all ingredients for chocolate cookie bars on marble counter
  • Butter
  • Brown Sugar
  • Granulated Sugar
  • Egg
  • Vanilla
  • Egg
  • Flour
  • Milk
  • Baking Powder
  • Cocoa Powder
  • Salt
  • Chocolate Chips
  • Heavy Cream
  • Powdered Sugar
  • Halloween Sprinkles

How To Make Halloween Bars

Step 1: Grease your 9×13 pan and preheat the oven as directed in the recipe card below.

cookie dough batter in mixing bowl

Step 2: In a bowl you will take your softened butter, brown sugar, granulated sugar, and mix up till light and fluffy. I used a mixer for this.

Step 3: Add in your eggs, vanilla and milk, and mix once again. Make sure it is well incorporated.

mixing up chocolate cookie bars

Step 4: Now in a new bowl add the dry ingredients in, and mix until blended. Then gradually add the dry to the wet ingredients.

Step 5: Pour in the chocolate chips and fold them in with a spatula. Then pour the mixture into your pan and make sure it is evenly spread.

Step 6: Bake as directed, and once done, allow your chocolate cookie bars to cool completely.

halloween cookie bars in pan

How to Make Homemade Buttercream Frosting

Step 1: Start by adding your butter in a mixer and whip until light and fluffy. Then add in the vanilla, salt, and cream.

Step 2: Once well mixed, slowly add in the powdered sugar to the mixture.

Step 3: Grab food coloring, I did orange, and drop in a few droplets. Mix again. Then add more coloring if needed to reach your desired color.

Step 4: Spread the frosting on top of the cooled cookie bars, and add on your favorite Halloween sprinkles.

Storing Leftovers

Refrigerate: Go right ahead and cover your cookie bars in an airtight container and store in the refrigerator. You will find the frosting can break down if left out at room temperature.

Freezer: These Halloween dessert bars also freeze well. Just slice into squares then freeze in a freezer bag or container. They will last 3-5 months in the freezer.

Thaw in the fridge overnight, or a quick thaw on the counter for an hour.

bitten cookie bar on plate with cookies bars behind it

Expert Tips & Variations

Here are some tips and tricks for making this Halloween snack. Along with variations if you want to change up the dessert.

  • The softened butter helps to cream well but also adds incredible richness to these cookie bars. Don’t use margarine to replace butter.
  • You do not have to add in the chocolate chips if you don’t want. This is a great dessert with chocolate chips that adds texture and sweetness. You can swap the chocolate chips with white chips, peanut butter chips, etc.
  • Feel free to use store bought cookie dough or even brownie mix if you don’t want to make these bars homemade. I personally love the homemade flavor.
  • If you don’t want to use the buttercream recipe for the frosting, use any store bought frosting. Or make your favorite homemade frosting.
  • Add on some candy eyes for more of a monster feel.


Best food coloring for frosting?

Wilton Concentrated Gel Food Coloring is wonderful add getting to control the color of your frosting, without altering the flavor. You can add a little for a light color, or more to make a richer colored frosting like these Halloween cookie bars.

How to know when cookie bars are done?

There are a few things to look for when you are not sure your cookie bars are done. The edges will begin to pull away from the pan. Also, take a toothpick and stick in the center, and lift. If the toothpick comes out clean of wet dough, the bars are done.

What if my frosting is too thin?

If your frosting seems a bit thin, add in more powdered sugar, and whip it up some more. Powdered sugar will thicken the frosting very quickly. Do a little at a time.

bars on parchment paper counter

Want More Halloween Recipes

stacked cookie bars on white plates on table

Halloween Bars Recipe

Yield: 9x13
Prep Time: 10 minutes
Cook Time: 12 minutes
Total Time: 22 minutes

Halloween Bars Recipe is a delicious double chocolate cookie bar that is topped with buttercream frosting. A fun and easy Halloween dessert that is kid friendly.


Cookie Bar Ingredients

  • ½ Cup Unsalted Butter (softened)
  • ½ Cup Brown Sugar
  • ½ Cup Granulated Sugar
  • 1 Egg
  • 2 teaspoons Vanilla
  • 2 tablespoons Milk
  • 2 Cups Flour
  • ½ Cup Cocoa Powder
  • 1 2 teaspoon Baking Powder
  • ½ teaspoon Salt
  • ½ Cup Chocolate Chips (optional)

Frosting Ingredients

  • ½ Cup Butter Unsalted (softened)
  • ½ teaspoon Vanilla
  • 6 tablespoons Heavy Cream
  • ¼ teaspoon Salt
  • 4 Cups Powdered Sugar
  • Orange Gel Food Coloring
  • Halloween Sprinkles


  1. Start by preheating the oven to 375 degrees. Then grease your 9x13 pan and set aside.
  2. In a stand mixer or with a hand mixer beat your brown sugar, granulated sugar, and butter together. This takes 2-4 minutes to make it light and fluffy.
  3. Add in egg, vanilla, and milk and mix well till combined.
  4. In a new bowl, add all your dry ingredients: flour, cocoa powder, baking powder, and salt. Whisk till mixed.
  5. Then slowly add the dry into the wet ingredients and mix until incorporated.
  6. Add in the chocolate chips and fold them in with a spatula.
  7. Place cookie bar dough in pan, and press down to spread it out evenly.
  8. Bake for 12-15 minutes or until the cookies are done. Allow the cookie bars to cool completely.
  9. To make the frosting whip up the softened butter for 2-3 minutes until soft and fluffy.
  10. Add in the vanilla, heavy cream, and salt. Then slowly add in the powdered sugar until it is thick and fluffy.
  11. Add in the orange food coloring, mix, and then add more if you want a darker color.
  12. Spread the buttercream frosting on top of the cooled chocolate cookie bars, and add on your Halloween sprinkles.
  13. Cut into squares and enjoy!


Butter: You can use salted butter in the cookie bars and the frosting. Just omit the salt to add into the bars and frosting if you do so.

Chocolate Chips: You do not have to add in the chocolate chips if you do not want. Or swap with white chips, peanut butter chips, etc.

Storage: The frosting will break down if left on the counter, I like to store these in an airtight container in the fridge. You can freeze the bars for 3-5 months.

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Nutrition Information:
Yield: 24 Serving Size: 1
Amount Per Serving: Calories: 253Total Fat: 11gSaturated Fat: 6gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 32mgSodium: 115mgCarbohydrates: 39gFiber: 1gSugar: 29gProtein: 2g

This information is automatically calculated by third-party software, including but not limited to the Create or Bake Me Some Sugar. For accurate nutrition, I suggest running the ingredients in your own system to get a more accurate reading. Nutritional information is approximate and automatically calculated, and should only be viewed as an indication.

Halloween Bars pictures
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