In a large mixing bowl or stand mixer using a dough hook, combine the flour, cornmeal, salt, sugar, and yeast. Gradually incorporate the warm water and melted butter, stirring on low speed until the dough forms.

Knead the mixture on low speed or with your hands until it becomes soft and elastic, roughly 4 to 5 minutes. Adjust the consistency if needed by adding warm water or flour in small amounts.

Coat a large bowl lightly with olive oil, place the dough inside, and turn to coat. Cover with aluminum foil and allow it to rise in a warm area until it doubles in size, which may take approximately 1 to 2 hours.

On a floured surface, gently press down the risen dough and roll it into a 15x12-inch rectangle. Spread softened butter across the surface, then roll the dough lengthwise into a log. Divide it into two pieces, shaping each into a ball before returning them to the greased bowl, covering, and refrigerating for an hour.

To prepare the sauce, melt butter in a saucepan over medium heat. Add the grated onion, salt, oregano, and red pepper flakes, cooking for around 5 minutes until the onions soften slightly and begin to color.

Stir in garlic, crushed tomatoes, and sugar. Reduce the heat to medium-low and allow the sauce to simmer uncovered, stirring occasionally, for about 30 minutes or until it thickens and develops a rich aroma.

Preheat the oven to 425°F (218°C). Take one ball of dough from the refrigerator and roll it out on a floured surface into a 12-inch circle, then fit it into a deep dish pan, pressing it gently against the sides and bottom. Trim any excess dough and lightly brush the edges with olive oil for added color.

Sprinkle half of the shredded mozzarella evenly over the bottom of the crust. Add your choice of toppings such as pepperoni and bacon, followed by a generous portion of sauce and a sprinkle of parmesan cheese on top.

Position the pan on a baking sheet to catch any drips and bake for 20 to 28 minutes until the crust is golden brown and crisp. If browning too quickly, cover loosely with foil halfway through baking.

Once out of the oven, allow the pizzas to cool in the pan on a wire rack for 10 minutes before slicing and serving. Leftovers can be stored in an airtight container in the fridge for up to 5 days and reheated at 300°F for 15 to 20 minutes.