M&M’s Peanut Butter Cake with Peanut Butter Frosting

This rich and fluffy peanut butter cake is loaded with colorful M&M’s and slathered in a dreamy peanut butter frosting — the perfect treat for peanut butter lovers and party celebrations alike!

Ingredients

For the Cake:

1/2 cup (1 stick) unsalted butter, softened

1/2 cup creamy peanut butter

1 cup granulated sugar

1/2 cup light brown sugar, packed

2 large eggs

1 tsp vanilla extract

1 1/4 cups all-purpose flour

1 tsp baking powder

1/2 tsp baking soda

1/4 tsp salt

1/2 cup buttermilk

1 cup M&M’s (plus extra for topping)

For the Peanut Butter Frosting:

1/2 cup (1 stick) unsalted butter, softened

1/2 cup creamy peanut butter

2 cups powdered sugar

2–3 tbsp milk or cream (as needed for consistency)

1/2 tsp vanilla extract

Pinch of salt

Instructions

Make the Cake Batter

Preheat oven to 350°F (175°C). Grease and flour a 9-inch round or square cake pan.

In a large bowl, cream together the butter, peanut butter, granulated sugar, and brown sugar until light and fluffy. Beat in the eggs and vanilla.

Combine Dry Ingredients

In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Add the dry ingredients to the wet mixture, alternating with buttermilk. Mix until just combined. Fold in the M&M’s.

Bake

Pour the batter into the prepared pan and smooth the top. Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Cool completely before frosting.

Make the Frosting

In a medium bowl, beat the butter and peanut butter until smooth. Add powdered sugar, one cup at a time, mixing until fluffy. Add milk and vanilla, beating until you reach your desired consistency. Add a pinch of salt to balance the sweetness.

Frost and Decorate

Spread the frosting over the cooled cake and sprinkle extra M&M’s on top for a colorful finish. Slice and serve!

Quick Look

Prep Time: 20 minutes

Cook Time: 35 minutes

Total Time: 55 minutes

Servings: 9–12

Calories: