Melt coconut oil in a saucepan over low heat, 3 to 5 minutes. Stir in peanut butter until smooth. Whisk in heavy cream, cocoa powder, liquid stevia, vanilla extract, and salt.
Pour chocolate-peanut butter mixture into 12 silicone muffin molds. Sprinkle peanuts evenly on top. Place molds on a baking sheet.
Freeze chocolate-peanut butter mixture until firm, at least 1 hour. Unmold chocolate-peanut cups and transfer to a resealable plastic bag or airtight container.