Preheat your oven to 350°F (175°C).
In a microwave-safe bowl, melt 3 ½ cups of mozzarella cheese for 1 to 2 minutes, then stir.
Mix one egg into the melted cheese using a spoon or electric mixer.
In another bowl, combine almond flour and baking powder. Gradually mix this into the cheese and egg mixture until fully combined. If you don’t have an electric mixer, knead the dough with your hands until it forms a ball.
Place the dough ball between two sheets of parchment paper and roll it out into a large rectangle, about ¼ inch thick.
Cut the dough into four rectangles using a pizza cutter or sharp knife.
On two rectangles, spread 1 tablespoon of keto pizza sauce, sprinkle with mozzarella cheese, and add 3-4 slices of pepperoni.
Cover with the plain rectangles, sealing the edges with your fingers and crimping with a fork. Repeat for the remaining dough.
Prick the tops of each pocket with a fork to let steam escape, then brush with egg wash.
Bake on parchment paper for 15-18 minutes until golden brown.
Allow to cool for 5 minutes before serving.