Step 1

Preparation Prepare a grill for medium-low heat. Set cast-iron griddle on grill. (Alternatively, heat on stovetop over medium-low. And if you don’t have a cast-iron griddle, use a cast-iron skillet instead and cook in batches.) Cut each piece of dough into quarters for 8 pieces total. Roll out 1 piece of dough to an 8x6" oval. Spoon a heaping 1/4 cup Fontina over half of dough and form a well in the center. Dab 2 Tbsp. ricotta and 1 Tbsp. nduja over Fontina, leaving well empty; slip a yolk into the well. Sprinkle with a bit of rosemary and drizzle with oil; season with salt. Moisten edges of dough with water, fold empty side of dough over filling and press together edges to seal. Brush with oil; sprinkle with salt. Repeat with remaining ingredients to make 7 more calzones.

Step 2

Place calzones, oiled side down, on griddle and cook until deeply browned, pressing gently with a spatula to create contact with griddle, about 5 minutes. Brush oil on the other sides and sprinkle with salt; turn calzones over. Cook until other sides are deeply browned, about 5 minutes. Transfer to a cutting board and let sit 1 minute before cutting in half.