Preheat your oven to 375°F (190°C) and lightly spray your muffin tin with olive oil spray to prevent sticking.
In a large mixing bowl, whisk together the unbleached all-purpose flour, baking powder, and kosher salt until well combined.
Add the Greek yogurt to the dry ingredients. Use a spatula to fold the mixture until it forms a soft dough. Be careful not to overmix.
Gently fold in the chopped turkey pepperoni, shredded mozzarella cheese, and marinara or pizza sauce until everything is evenly distributed.
Scoop the mixture into the prepared muffin tin, filling each cup about three-quarters full. This allows enough space for the bites to rise while baking.
Place the muffin tin in the preheated oven and bake for 15-20 minutes, or until the tops are golden brown and a toothpick inserted in the center comes out clean.
Let the Pepperoni Pizza Bites cool in the tin for a few minutes before transferring them to a wire rack. Serve warm, sprinkled with crushed red pepper flakes if desired.