Line 10 cups of a 12-cup mini-cupcake tin with parchment paper cups.
Combine peanut butter, 2 tablespoons ghee, and 1/2 tablespoon of stevia in a small microwave-safe bowl until smooth. Heat in a microwave for 10 to 15 seconds, if necessary. Pour mixture into the lined mini-cupcake cups, filling each halfway. Place tin in the freezer while you make topping.
Combine remaining 2 tablespoons ghee and chocolate in a microwave-safe bowl. Heat in the microwave on high in 15-second intervals, stirring after each, until chocolate is soft and mixes easily with ghee. Stir in remaining 1 tablespoon stevia and heavy cream and mix until smooth.
Remove cupcake tin from freezer. Fill the rest of each cup with chocolate mixture. Return tin to freezer for at least 30 minutes. Store peanut butter cups in an airtight container in the freezer or refrigerator.
