In a small bowl, combine the yeast, sugar, and lukewarm water. Stir and let sit for 5-10 minutes until foamy.

In a large mixing bowl, combine the flour, cornmeal, and salt. Add the yeast mixture, melted butter, and olive oil. Mix until a dough forms.

Knead the dough on a lightly floured surface for 5-7 minutes until smooth and elastic.

Place the dough in a lightly oiled bowl, cover with a clean kitchen towel or plastic wrap, and let rise in a warm place for 1-2 hours, or until doubled in size.

Heat olive oil in a medium saucepan over medium heat. Add the grated onion, oregano, and crushed red pepper flakes (if using). Cook for 2-3 minutes until the onion softens.

Add the minced garlic and cook for 30 seconds until fragrant.

Stir in the crushed tomatoes and tomato paste. Season with salt and pepper to taste.

Reduce the heat to low and simmer for 20-25 minutes, stirring occasionally, until the sauce thickens. Remove from heat and set aside.

Preheat your oven to 425°F (220°C). Grease a 12-inch deep dish pizza pan or cast-iron skillet with olive oil.

Punch down the risen dough and roll it out into a 14-inch circle. Carefully press the dough into the prepared pan, ensuring it covers the bottom and sides. Trim any excess dough hanging over the edges.

Layer the shredded mozzarella cheese evenly over the bottom of the crust.

Add the cooked and crumbled Italian sausage on top of the cheese.

Spread the prepared tomato sauce evenly over the sausage layer.

Sprinkle the grated Parmesan cheese over the sauce.

Bake the pizza in the preheated oven for 35-40 minutes, or until the crust is golden brown and the cheese is bubbling.

Remove the pizza from the oven and let it cool for 5-10 minutes before slicing and serving.