Instructions:
Make peanut butter filling: Combine peanut butter, powdered sugar, butter, and vanilla extract in a bowl. Mix well.
Shape filling: Shape peanut butter filling into small balls (about 1 inch in diameter). Place on a parchment-lined baking sheet.
Melt chocolate: Melt dark chocolate in a microwave-safe bowl in 30-second intervals, stirring well.
Assemble cups: Line a muffin tin with paper or silicone liners. Spoon a small amount of melted chocolate into each liner. Place a peanut butter ball on top. Spoon more melted chocolate over the peanut butter filling.
Cool and set: Place muffin tin in the refrigerator for at least 30 minutes. Remove peanut butter cups from liners and store in an airtight container in the refrigerator.
