Step 1: Line a 12-cup mini muffin tin (or 6-cup standard muffin tin) with paper liners.
Step 2: Melt half of the chocolate chips. Spoon about 1 teaspoon (for mini) or 1 tablespoon (for regular) into the bottom of each liner. Tap the tin to spread evenly. Freeze for 5-10 minutes to set.
Step 3: In a medium bowl, combine peanut butter, powdered sugar, and melted butter (or coconut oil). Mix until smooth and creamy.
Step 4: Roll the peanut butter mixture into small balls (about ½ tablespoon for mini, 1 tablespoon for regular). Flatten each ball slightly into a disc. Chill on a parchment-lined plate for 10-15 minutes.
Step 5: Place one chilled peanut butter disc on top of each set chocolate base in the muffin tin. Gently press down.
Step 6: Melt the remaining chocolate. Spoon it over the peanut butter filling, ensuring it’s completely covered and meets the edges of the bottom chocolate layer. Smooth the top with a spoon. Optionally, sprinkle with flaky sea salt.
Step 7: Refrigerate for at least 30-60 minutes, or until completely set. Once firm, peel off the liners and enjoy. Store in an airtight container in the refrigerator.