To prepare the crust:

• Lightly grease a large bowl with olive oil. Set aside.
• In the bowl of a stand mixer fitted with the dough hook attachment, combine the flour, cornmeal, salt, sugar and yeast. Add the lukewarm water and 1/8 cup of melted butter. Beat the ingredients on low speed until it falls off of the hook, about 5 minutes.
• Remove the dough, and lightly form into a ball. Place the dough into the prepared bowl. Roll the ball in the bowl to coat it in olive oil.
• Cover the bowl, and store it in a warm dry place until it doubles in size, about 1 hour.
• Lightly flour a work surface. Remove the dough, and lightly punch it down.
• Using a rolling pin, roll the dough into a 11×8-inch rectangle. Spread 1/8 cup of softened butter over the dough. Roll the dough lengthwise, and return to the greased bowl.
• Transfer the bowl to the refrigerator, and chill about 1 hour.

To prepare the sauce:

• In a medium saucepan over medium heat, melt the butter. Add the grated onion, salt, oregano and red pepper flakes. Heat for 5 minutes. Add the garlic, tomatoes and sugar.
• Reduce heat to medium-low, and simmer the mixture until it thickens, about 30 minutes. Remove from heat. Set aside.

To prepare the pizza:

• Preheat oven to 425 degrees F.
• Lightly roll the dough on a floured service. Roll the dough into a 12-inch round circle.
• Place the dough over a 9×2-inch deep dish cake pan. Press the dough into the pan.
• Brush the top edges of the dough with olive oil.
• Fill the pizza crust with the mozzarella cheese, green pepper, pepperoni and mushrooms.
• Pour the tomato sauce over the toppings. Top with the parmesan cheese.
• Bake the pizza until the crust is golden brown, about 18 minutes.
• Allow the pizza to cool in its pan on a wire rack for 10 minutes.
• Slice and serve warm.