Step 1

In a heatproof bowl set over barely simmering water, melt the chocolate and cocoa butter together, stirring until smooth.

Step 2

Use the back of a small spoon to spread a little over half of the chocolate mixture on the bottom and up the sides of the candy molds. Freeze 10 minutes.

Step 3

In a microwave safe bowl, melt the peanut butter and butter together on high in 30 second increments, stirring until smoth. Whisk in the powdered sweetener and vanilla extract.

Step 4

Remove the chocolate cups from freezer and fill almost to the top with the peanut butter mixture, leaving enough space to cover with remaining chocolate. Return to freezer for another 10 minutes or so.

Step 5

Rewarm the remaining chocolate gently over low heat and stir until smooth. Spread over the peanut butter filling to the sides of each cup. Chill until set, 20 minutes.