Mix together the gluten-free bread flour blend, granulated sugar, kosher salt, and rapid rise yeast until well combined.

Gradually add the milk and melted butter to the dry mixture using a stand mixer fitted with a paddle attachment, mixing on low then medium until smooth.

Cover and let the dough rise in a warm area for about 2 hours.

Preheat the oven to 400°F (200°C).

Pour olive oil into a 12-inch cast iron skillet, ensuring the bottom is well-coated.

Transfer half of the risen dough into the oiled pan and dimple it with fingertips.

Cover the pan and let the dough rest for another 30 minutes.

Sprinkle chopped rosemary, sea salt, cracked black pepper, and grated Parmigiano Reggiano on top of the dough.

Bake in the preheated oven for 25-30 minutes or until golden brown.

Cool slightly in the pan for about 10 minutes before serving.