Preheat oven at highest setting (for me that's 550°F/290°C) with pizza steel/stone.
Grate mozzarella on largest holes of box grater. Place grated cheese in the freezer for about 45 minutes.
Flour work surface and one of the doughs, and flip it out on to your work surface and flour the wet/non-floured side of the dough.
Flatten dough with your hand then with a rolling pin, roll out into about a 10"/25cm round. Finish stretching the dough by hand until it is about a 12"/30cm round.
Load dough onto pizza peel that has been well dusted with semolina flour.
Spread about 2 cups/240g of the chilled shredded cheese onto the dough followed by a generous pinch of grated parm. Add several large spoonfuls of the pizza sauce (about 120g/½ cup total per pizza). Spread slightly, making sure to leave plenty of the surface un-sauced. Load onto the pre-heated pizza steel/stone and cook for 6 minutes. Bottom should be well crisped up. Place onto a wire rack to cool slightly before cutting.