Preheat the oven and line the pan: Begin by preheating your oven to 350°F (or according to the instructions on your cupcake mix). While the oven heats, line a 12-cup muffin tin with paper cupcake liners. This helps ensure the cupcakes bake evenly and release easily after baking.

Prepare the cupcake batter: In a large mixing bowl, prepare the chocolate cupcake batter as instructed on the box. Usually, you'll need to mix in eggs, oil, and water. Stir the ingredients until just combined avoid overmixing to keep the texture light and fluffy.

Add the surprise center: Place one unwrapped mini peanut butter cup flat side down in the center of each cupcake liner. You can gently press it into the liner so it stays centered when the batter is added.

Fill and bake: Carefully spoon the prepared batter into each liner, filling to about 3/4 full, completely covering the peanut butter cup. Place the muffin tin in the oven and bake for 18–20 minutes or until a toothpick inserted near the edge (not the center) comes out clean. The peanut butter cup may soften or melt slightly, which is perfectly fine!

Cool and frost: Remove cupcakes from the oven and allow them to cool in the pan for 5–10 minutes before transferring them to a wire rack to cool completely. Once fully cooled, use a piping bag or spatula to generously frost each cupcake with the peanut butter frosting. Add an extra mini peanut butter cup on top if you like!