Preheat your oven to 400°F. Grease a standard 12-cup muffin tin and set it aside.

In a large bowl, whisk together the flour blend, xanthan gum, baking powder, and salt.

Add the yogurt and 2 tablespoons of water to the dry mix. Stir until the dough holds together. If dry, add another tablespoon of water.

Divide the dough into two equal portions, covering one half with plastic wrap.

On a flat work surface lightly sprinkled with gluten-free flour, roll out the first portion of dough into a rectangle about 1/4-inch thick.

Fold the dough over on itself at least once, then roll again to ensure a smooth texture.

Roll the dough into a rectangle about 10-inches long by 8-inches wide, dusting with flour as necessary.

Spread half of the tomato sauce over the dough, leaving a 1-inch border around the edges.

Add half of the pepperoni, half of the Parmigiano-Reggiano, and the mozzarella cheese, pressing fillings down slightly.

Starting from one short end, roll the dough tightly into a coil and slice it into 6 equal portions.

Place each pinwheel cut side up in the prepared muffin tin, pressing them lightly into their wells.

Repeat with the second half of the dough and remaining filling ingredients.

Brush the tops and sides of each pinwheel with the egg wash.

Place the muffin tin in the oven and bake for about 22 minutes, or until the pinwheels are firm and golden brown, with bubbling cheese.

Allow the pinwheels to cool slightly before serving them warm.