Place the chocolate chips and coconut oil in a microwave safe bowl. Microwave for 20-second increments, stirring between increments, until melted and completely smooth (this will take about 40 to 60 seconds total).

Line a muffin tray with muffin papers. Spoon a thin layer of melted chocolate onto the bottoms of the muffin papers. Place in the freezer for at least 15 minutes, or until the chocolate has set up.

While the chocolate is setting up, mix up the peanut butter mixture. In a small bowl or ramekin, stir together the peanut butter and protein powder (or coconut flour) until completely combined. The mixture should be thick and no longer sticky (it should leave a light layer of grease on your hands, but not stick to them). If the mixture is very sticky, add more protein powder or coconut flour.

Divide the peanut butter mixture into even-sized balls (again, if you’re making large peanut butter cups, you’ll want 6 balls of peanut butter). Press the balls on top of the bottom chocolate layer, and press the peanut butter into an even layer. Cover with melted chocolate, then sprinkle with coarse sea salt.

Refrigerate for 1 hour, or freeze at least 15 minutes, until peanut butter cups have set up completely.