Please read through the recipe completely before beginning. You will need two deep dish 9x2-inch round cake pans if you are making both pizzas at the same time. You can also use 9-inch springform pans.
For the crust: Combine the flour, cornmeal, salt, sugar, and yeast in the bowl of a stand mixer fitted with a dough hook attachment. If you do not have a stand mixer, use your hand mixer and a very large bowl. If you do not have any mixer, you can do this all by hand. Again, use a very large bowl. Give those ingredients a quick toss with your mixer on low or with a large wooden spoon. Add the warm water and 1/4 cup of melted butter. The warm water and melted butter should be around 120-130°F. On low speed, mix (or stir) the dough ingredients until everything begins to be moistened. Continuing on low speed (or remove from the bowl and knead by hand if you do not own a mixer), knead the dough until it is soft and supple and gently pulls away from the sides of the bowl and falls off of the dough hook- about 4-5 minutes. If the dough is too hard (it will be textured from the cornmeal), but if it feels too tough, knead in a teaspoon of warm water. Alternatively, if it feels too soft, knead in a tablespoon of flour.
Remove the dough from the bowl and form into a ball. Lightly grease a large mixing bowl with olive oil and place the dough inside, turning it around so that all sides of the dough are coated in the oil. Cover tightly with aluminum foil or plastic wrap and allow to rise in a warm environment for 1-2 hours or until double in size.
Once the dough is ready, lightly flour a large work surface. Remove dough from the bowl, set the bowl and aluminum foil/plastic wrap aside (to use later). Gently punch down the dough to remove any air bubbles and roll the dough into a large 15x12-inch rectangle. Spread 1/4 cup of softened butter on top of the dough. Roll it up lengthwise. Cut the dough log in half. Form the two pieces of dough into balls and place back into your greased bowl. Cover with aluminum foil/plastic wrap and allow to rise in the refrigerator (not in a warm place) for 1 hour until they are puffy as you make the sauce.
For the sauce: Place butter in a medium saucepan over medium heat and allow it to melt. Once melted, add the grated onion, salt, oregano, and red pepper flakes. Once the onion has slightly browned after about 5 minutes, add the garlic, tomatoes, and sugar. Turn the heat down to low-medium and allow it to simmer until it's hearty, fragrant, and thick- about 30 minutes. You'll have about 2 and 1/2 cups of sauce at this point. If you have more than that, keep simmering until the amount has reduced. Remove from heat and set aside until ready to be used. You may store the sauce in a tightly covered container in the refrigerator for up to 2 days if planning to make the pizza another day. You may freeze this sauce for up to 2 months as well.
Preheat oven to 425°F.
Assemble the pizzas: After the dough balls have risen in the refrigerator, they should be puffy. Keep one ball of dough in the refrigerator as you work with the first one. Roll it out on a lightly floured work surface, working it into a 12-inch circle. Using your rolling pin as a guide, place over a greased 9x2-inch deep dish cake pan. Using your fingers, press the dough into the cake pan. Make sure it is nice and tight fitting inside the pan. Trim any excess dough off the edges with a small knife. Repeat with 2nd dough. Brush the top edges of the dough with a little olive oil, which gives the crust a beautiful sheen. Fill each pizza with 1/2 of the cheese (about 2 cups per pizza), then your toppings which are listed as optional in the recipe ingredients. On top of those optional toppings is the sauce. Pour about 1 and 1/4 cups of sauce on top of each pizza. If you do not like that much sauce, you can reduce to 3/4 cup per pizza and have leftover sauce. Sprinkle each with 1/4 cup of grated Parmesan cheese.
Place the cake pans on top of a large baking sheet with sides, which will catch anything potentially spilling over the sides of the cake pans. Bake for 20-28 minutes or until the crust is golden brown. Feel free to loosely cover the pizzas with aluminum foil after the 15 minute mark to prevent any heavy browning and uneven baking. Remove the pizzas from the oven and allow to cool in the pans placed on a wire rack for 10 minutes. After 10 minutes, slice, serve, and enjoy.
Place any leftover pizza in an airtight container and refrigerate for up to 5 days. Reheat in a 300°F oven for 15-20 minutes or until hot.