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

Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans (or line with parchment paper) to prevent sticking.

In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, use an electric mixer to beat together the peanut butter, unsalted butter, and granulated sugar until light and fluffy, about 2-3 minutes.
Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
Alternately add the dry ingredients and milk to the peanut butter mixture, starting and ending with the dry ingredients. Mix until just combined.
Fold in the sour cream and M&M’s (reserving a handful for topping the cake).

Divide the cake batter evenly between the prepared cake pans.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center of the cakes comes out clean.
Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

In a medium bowl, beat together the peanut butter and unsalted butter with an electric mixer until smooth and creamy, about 2 minutes.
Gradually add powdered sugar, one cup at a time, mixing until smooth and creamy. Add vanilla extract and mix well.
Add milk or heavy cream a tablespoon at a time to reach your desired frosting consistency (you want it thick but spreadable).

Once the cakes are completely cooled, spread a layer of peanut butter frosting on top of the first cake layer.
Place the second cake layer on top and frost the entire cake with the remaining peanut butter frosting.
Sprinkle the top with reserved M&M’s and any additional decorations you’d like.

Slice and serve the cake! It’s best served at room temperature, but you can store leftovers in an airtight container at room temperature for 2-3 days or refrigerate for up to 5 days.