In the bowl of a stand mixer fitted with the dough hook, combine the flour, cornmeal, yeast, sugar, and salt. Mix on low speed until blended.

Add the warm water and 3 tablespoons of melted butter. Mix on low until combined, about 1 to 2 minutes. Scrape down the sides of the bowl, then increase speed to medium and knead until the dough is shiny, smooth, and pulls away from the sides of the bowl, about 4 to 5 minutes.

Coat a large bowl with 1 teaspoon of olive oil. Transfer the dough to the bowl, turning to coat. Cover with plastic wrap and let rest at room temperature until nearly doubled in size, about 1 hour.

While the dough rises, heat 1 tablespoon olive oil and 1 tablespoon butter in a medium saucepan over medium heat. Add the minced red onion, crushed red pepper flakes, Italian seasoning, salt, and pepper. Cook, stirring frequently, until the onion is softened, about 5 minutes.

Add the minced garlic and cook until fragrant, about 30 seconds. Stir in the crushed tomatoes and sugar. Bring to a simmer, then reduce heat to medium-low and cook, stirring occasionally, until the sauce thickens to about 2 1/2 cups, about 30 minutes.

Remove from heat and stir in the chopped basil and remaining 1 tablespoon olive oil. Taste and adjust salt if needed. Cover and set aside.

Adjust the oven rack to the lowest position and preheat the oven to 425°F. Turn the risen dough out onto a clean countertop. Roll it into a 15 by 12-inch rectangle.

Using an offset spatula, spread the 4 tablespoons of softened butter over the dough, leaving a 1/2-inch border along the edges. Starting at the short end, tightly roll the dough into a cylinder. With the seam side down, flatten the cylinder into an 18 by 4-inch rectangle. Cut the rectangle in half crosswise.

Working with one half at a time, fold the dough into thirds like a business letter. Pinch the seams together to form a ball. Repeat with the remaining half. Place both balls in the oiled bowl, cover tightly with plastic wrap, and refrigerate until nearly doubled in size, 45 to 50 minutes.

While the dough chills, cook the Italian sausage in a large nonstick skillet over medium-high heat, breaking it into crumbles. Cook until browned and cooked through, then drain well and set aside.

Coat two 9-inch cast iron skillets or round cake pans with 1 1/2 tablespoons of olive oil each.

On a clean countertop, roll one dough ball into a 13-inch round disk about 1/4-inch thick. Roll the dough loosely around the rolling pin and transfer to one of the prepared skillets. Gently press the dough into the pan, working it into the corners and up the sides about 1 inch. If the dough resists, let it rest for 5 minutes before continuing. Repeat with the remaining dough ball.

Sprinkle each pizza with 2 cups of shredded mozzarella. Divide the sauce evenly between the two pizzas, spreading it with the back of a spoon over the cheese. Divide the cooked Italian sausage between the pizzas, scattering it over the sauce. Top with the sliced olives and then the grated Parmesan.

Bake until the crust is golden brown, about 20 to 30 minutes. If the top browns too quickly, tent the pizzas with foil. Remove from the oven and let cool for 10 minutes before slicing and serving.