Preheat oven to 350 degrees F. Line a baking sheet with parchment paper or a silicone baking mat. 

In a stand-mixer bowl, combine the flour, baking powder, and salt. Add the yogurt and mix with a paddle attachment until dough comes together into a sticky ball. 

Lightly dust flour on a work surface and turn the dough out on surface, knead the dough until the dough is smooth and no longer sticky, using more flour as needed to make dough smooth. 

Divide dough into 4 equal balls. Roll the each ball into a thin rectangle – it doesn't have to be perfectly shaped. Divide mozzarella, pepperoni, and bell peppers between all the rectangles. Starting with a long side, roll the dough up tightly and pinch the seams and ends to seal. Place on the prepared baking sheet and brush with egg. Sprinkle each roll with Italian seasoning.

Bake for 30-35 minutes. Let cool at least 15 minutes before cutting. Serve with red pepper flake.