Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a large mixing bowl, whisk together the all-purpose flour, unsweetened cocoa powder, granulated sugar, baking powder, baking soda, and salt.
In a separate bowl, whisk together the melted unsalted butter, eggs, whole milk, and vanilla extract until smooth.
Gradually pour the wet mixture into the dry ingredients, stirring gently until just combined.
Evenly divide the batter among the lined muffin cups, filling each about two-thirds full.
Bake for 18-20 minutes, checking for doneness with a toothpick.
While the cupcakes cool, prepare the peanut butter frosting by beating together the creamy peanut butter and powdered sugar, then gradually adding the heavy cream until desired consistency is reached.
Once the cupcakes are cool, frost them with the peanut butter frosting.
Garnish with chocolate shavings or crushed peanuts if desired.
Notes
For an elegant touch, garnish with chocolate shavings or crushed peanuts.