Method

1. In a small saucepan over low heat, melt butter, unsweetened chocolate and powdered erythritol together, stirring until smooth. Stir in cocoa powder, vanilla and stevia extract. Let cool 5 to 10 minutes, until somewhat thickened.
2. Use back of small spoon to spread chocolate mixture on bottom and up sides of twelve 1 ½ inch plastic-lined candy cups or candy molds (whatever you use needs to be firm enough to stand up against the warm chocolate and not lose its shape). Place on baking sheet or platter and freeze until firm, about 20 minutes.
3. In a microwave safe bowl, heat peanut butter on high for 30 seconds or until fully melted but not hot. Stir in powdered erythritol and vanilla extract.
4. Remove chocolate cups from freezer and fill almost to the top with peanut butter mixture, leaving enough space to cover with remaining chocolate. Return to freezer for another 10 minutes or so.
5. Rewarm remaining chocolate gently over low heat and stir until smooth. Spread over peanut butter filling to the sides of each cup. Chill until set, 20 minutes.
6. Store in the refrigerator.