In a large bowl, combine the flour, sugar, yeast, and salt.
Gradually add the warm (not hot) water and olive oil to the flour mixture, stirring with a wooden spoon until a shaggy dough forms.
Turn the dough out onto a lightly floured surface and knead for 4-6 minutes, until the dough is smooth.
Place the dough ball in a large, lightly oiled bowl and cover with a kitchen towel. Let the dough rise in a warm, draft-free place for 1-2 hours, or until doubled in size.
Preheat your oven to 425°F (218°C).
Place a 12 inch cast iron skillet in the oven to preheat.
On a lightly floured surface, roll out the pizza dough to fit the size of your skillet.
Remove the skillet from the oven and carefully brush the bottom and sides with 1 tablespoon of olive oil.
Carefully transfer the rolled-out dough to the skillet and press it against the bottom and sides of the skillet.
Spread the pizza sauce evenly over the dough, leaving a small border around the edges.
Sprinkle the shredded mozzarella cheese on top of the sauce, followed by the grated Parmesan cheese, dried oregano, garlic powder, and red pepper flakes.
If making pepperoni pizza: Arrange the pepperoni slices on top of the cheese.
Drizzle the remaining tablespoon of olive oil over the top of the pizza.
Place the skillet in the oven and bake for 20-25 minutes, or until the crust is golden brown and the cheese is melted and bubbly.
Remove the skillet from the oven and let it cool for a few minutes before slicing and serving.