Preheat the oven to 350°F (177°C). Line a large baking sheet with parchment paper.

Add chocolate chips to a microwave-safe mixing bowl. Melt chocolate in the microwave in 15-30 second increments, stirring in between with a silicone spatula, until chocolate is fully melted and smooth. Set aside.

Add egg to the bowl of a stand mixer. Beat on highest speed for 3 minutes. When finished, your mixture should be thick and pale yellow. When you lift the beater, the liquid that drips off should hold its form for several seconds on top of the egg batter (see photo in post for reference).

Add the peanut butter, melted chocolate and baking powder to your egg mixture. Very gently fold the mixture with a silicone spatula until everything is incorporated and no egg streaks remain. Try your best not to deflate too much of the egg mixture. Your batter should resemble a thick chocolate spread (see photo in post for reference).

Use a 1.5 tbsp cookie scoop to scoop the cookie batter and release onto your prepared baking sheet, spacing the cookies about 2 inches apart. If your released cookie batter has some little stray bits of batter sticking up, you can gently smooth them down with your finger.

Bake cookies for 8-10 minutes or until the cookies are puffed and set around the edges. Allow cookies to cool slightly before serving. Cookies taste best soon after they are baked. The cookies do tend to get a little drier and more crumbly the longer you store them. Uneaten cookies should be stored in an airtight container for 1-2 days at room temperature and longer in the fridge or freezer. I also recommend briefly reheating any leftover cookies before eating them.