01 -
Preheat the oven to 175°C (350°F). Grease and flour two 9-inch round cake pans.
02 -
In a bowl, whisk together flour, baking powder, baking soda, and salt.
03 -
In a large bowl, beat together butter and peanut butter until creamy. Gradually add sugar, beating until fluffy.
04 -
Add eggs one at a time, beating well after each addition. Stir in vanilla extract.
05 -
Add the dry ingredients alternately with buttermilk to the peanut butter mixture, beginning and ending with the dry ingredients. Mix until just combined.
06 -
Gently stir in M&M's.
07 -
Divide the batter evenly between the prepared pans. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
08 -
Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.
09 -
In a large bowl, beat together butter and peanut butter until creamy. Gradually add powdered sugar, beating until smooth. Add heavy cream and vanilla extract, beating until fluffy.
10 -
Spread frosting on the top of one cake layer. Place the second layer on top and frost the top and sides of the cake.
11 -
Sprinkle additional M&M's on top of the frosted cake.