Step 1: Prepare for Baking

Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with cupcake liners to ensure easy removal and a neat presentation.

Step 2: Mix the Dry Ingredients

In a large mixing bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt. This step ensures even distribution of the leavening agents for a uniform rise in your cupcakes.

Step 3: Combine the Wet Ingredients

In a separate bowl, mix the granulated sugar, brown sugar, and vegetable oil until smooth. Whisk in the eggs one at a time, followed by the milk and vanilla extract. The mixture should be creamy and well-blended.

Step 4: Make the Batter

Gradually add the dry ingredients to the wet ingredients. Mix just until combined—overmixing can result in dense cupcakes. The batter will be thick and rich.

Step 5: Bake the Cupcakes

Divide the batter evenly among the prepared cupcake liners, filling each about two-thirds full. Bake for 18–20 minutes, or until a toothpick inserted into the center comes out clean. Allow the cupcakes to cool completely on a wire rack before frosting.

Step 6: Make the Peanut Butter Frosting

In a large bowl, beat the softened butter and peanut butter together until smooth and creamy. Gradually add the powdered sugar, beating well after each addition. Add milk, one tablespoon at a time, to reach your desired frosting consistency. Stir in the vanilla extract for a final touch of flavor.

Step 7: Frost and Decorate

Once the cupcakes are completely cool, use a piping bag or a spatula to frost each cupcake. Be generous—the frosting is the star here! Top each frosted cupcake with a sprinkle of crushed Butterfinger pieces. For extra flair, press a larger piece of Butterfinger into the frosting.