Dissolve yeast and sugar in warm water; let soften for 15 minutes.

Combine olive oil, salt, and milk in a bowl.

Mix flour and cornmeal in a large bowl.

Add yeast and olive oil mixtures to the flour, stir to form a rough dough.

Knead the dough on a floured board for 6-8 minutes until smooth.

Oil a bowl, place the dough inside, and cover with plastic wrap.

Let rise in a warm place for 35-40 minutes until doubled.

Divide the dough into 2 portions.

Roll out the first half to 1/4-inch thickness.

Cut out 5-inch rounds with a biscuit cutter.

Re-roll scraps once.

Repeat with the second half of the dough to yield 10 disks.

Cover disks with parchment or cloth; let rest for 10 minutes.

Divide mozzarella into 10 portions, place on half of each disk.

Add pecorino, prosciutto, and tomatoes to the mozzarella.

Season with pepper.

Fold disks in half to form half-moons.

Seal edges with your finger.

Cover with parchment or cloth.

Preheat oven to 150 degrees F.

Heat olive oil in a heavy-bottomed saucepan until almost smoking.

Add 3-4 panzarotti at a time and cook until browned, turning to brown evenly.

Remove to a paper towel-lined tray and keep warm in the oven until serving.