In a large bowl, combine the flour, cornmeal, sugar, yeast, and salt.
Add the warm water and 1/4 cup olive oil to the dry ingredients and stir until a dough forms.
Turn the dough onto a floured surface and knead for about 8 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a clean towel, and let rise in a warm place for 1 hour or until doubled in size.
While the dough rises, prepare the sauce: heat 1 tablespoon olive oil in a skillet over medium heat.
Add the Italian sausage and cook, breaking it apart, until browned and cooked through, about 7 minutes.
Add the chopped onion and cook until softened, about 5 minutes.
Stir in the minced garlic and cook for 1 minute until fragrant.
Add the crushed tomatoes, oregano, dried basil, salt, and black pepper.
Simmer the sauce over low heat for 20 minutes, stirring occasionally.
Preheat the oven to 425°F (220°C).
Grease a 12-inch deep dish pizza pan or a cast-iron skillet with olive oil.
Punch down the risen dough and press it into the prepared pan, pushing the dough up the sides to create a thick crust.
Sprinkle half of the shredded mozzarella cheese evenly over the dough.
Spread the cooked sausage and tomato sauce mixture evenly over the cheese layer.
Sprinkle the remaining mozzarella cheese and grated Parmesan cheese on top.
Bake the pizza in the preheated oven for 35 to 40 minutes, or until the crust is golden brown and the cheese is bubbly and slightly browned.
Remove the pizza from the oven and let it cool for 5 minutes.
Sprinkle chopped fresh basil over the top before slicing and serving.