Step 1

Preheat the oven to 350°F (177°C). Line a 12-cup muffin pan with cupcake liners. Line a second pan with 2-3 liners because this recipe yields 14-15 cupcakes. Set aside.

Step 2

Whisk the flour, baking soda, and salt together in a medium bowl. Set aside.

Step 3

Using a handheld mixer, stand mixer fitted with a whisk or paddle attachment, or a whisk, mix the oil, peanut butter, brown sugar, egg, sour cream, and vanilla extract together in a large bowl. Add the dry ingredients, milk, and peanuts and whisk or beat together until completely combined. Avoid overmixing. Batter will be slightly thick.

Step 4

Pour/spoon the batter into the liners, filling only 2/3 full to avoid baking over the sides. Bake for 21-23 minutes, or until a toothpick inserted in the center comes out clean and the tops of the cupcakes spring back when gently touched. For around 35 mini cupcakes, bake for about 11-13 minutes, same oven temperature. Allow the cupcakes to cool completely before frosting.

Step 5

With a handheld or stand mixer fitted with a paddle or whisk attachment, beat the butter on medium speed until creamy, about 2 minutes. Add confectioners’ sugar, cocoa powder, and milk. Beat on low speed for 30 seconds, then add the peanut butter, vanilla extract, and salt. Beat on medium-high speed for 2 minutes until combined. Add 1/4 cup more confectioners’ sugar if frosting is too thin or another 1-2 Tablespoons of cream/milk if frosting is too thick. Taste. Add extra peanut butter or a pinch of salt if desired.

Step 6

Frost cooled cupcakes. I piped a basic tall swirl using Ateco 849 piping tip. You can watch me decorate the cupcakes in the video in the blog post. Garnish with peanut butter cup, if desired.

Step 7

Cover and store leftovers in the refrigerator for up to 5 days.