Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a large mixing bowl, whisk together the flour, cocoa powder, granulated sugar, baking powder, baking soda, and salt until well combined.
In another bowl, mix the melted butter, eggs, milk, and vanilla extract until smooth.
Gradually add the wet mixture to the dry ingredients, stirring gently just until combined. Do not overmix.
Divide the batter evenly among the cupcake liners, filling each about 2/3 full.
Bake in the preheated oven for 18-20 minutes or until a toothpick inserted in the center comes out clean.
While the cupcakes cool, prepare the peanut butter frosting. In a medium bowl, beat together the peanut butter and powdered sugar, adding the heavy cream gradually until the desired consistency is achieved.
Once the cupcakes are completely cooled, generously pipe or spread the peanut butter frosting on top of each cupcake.
If desired, garnish with chocolate shavings or a sprinkle of crushed peanuts for an extra touch of flavor and presentation.
Notes
For an extra touch, garnish with chocolate shavings or crushed peanuts.