Step 1: Prepare Your Oven and Liners - Preheat your oven to 350°F (175°C) and line your cupcake pan with cupcake liners.
Step 2: Combine Dry Ingredients - In a large mixing bowl, whisk together the cake flour, granulated sugar, brown sugar, baking powder, baking soda, and salt.
Step 3: Mix Wet Ingredients - In another bowl, mix the melted butter, vegetable oil, creamy peanut butter, and eggs. Add vanilla extract, sour cream, and buttermilk, whisking until smooth.
Step 4: Combine Wet and Dry Mixtures - Gradually add the wet mixture to the dry ingredients, stirring gently until just combined.
Step 5: Fold in the Chocolate Chips - Gently fold in the miniature chocolate chips.
Step 6: Fill the Cupcake Liners - Fill each cupcake liner about two-thirds full with batter.
Step 7: Bake - Bake for 18-20 minutes or until a toothpick comes out clean.
Step 8: Cool the Cupcakes - Let them cool in the pan for 5 minutes before transferring to a cooling rack.
Step 9: Prepare the Frosting - Beat together the creamy peanut butter and softened butter until smooth, then gradually add powdered sugar and salt.
Step 10: Frost and Garnish - Once cooled, frost the cupcakes and sprinkle additional miniature chocolate chips on top.