Line a muffin tray with cupcake liners. Combine chocolate chips and 1 tbsp. coconut oil in a large microwave-safe bowl. Microwave on high, stirring every 30 seconds, until chocolate is smooth and melted completely. Spoon 1 ½ tbsp. melted chocolate into each cupcake liner. Gently tilt cupcake tin in a circular motion to coat the bottom 2/3 of the cupcake liners. Place in refrigerator to harden, 10 minutes. Meanwhile, stir together peanut butter and remaining coconut oil (melted) until smooth. Transfer to piping bag or a medium resealable bag. When chocolate layer is set, pipe about 1 tablespoon of peanut butter into a round disc on top of the chocolate in the cupcake liner. Reheat remaining chocolate, if needed, then spoon 1 tablespoon over each peanut butter disk and smooth into an even layer. Repeat until all chocolate is used and return to refrigerator to harden, 15 more minutes.