Preheat oven to 500 degrees and put olive oil in a 12" cast iron skillet (see notes if using smaller or larger skillet). Use a pastry brush or paper towel (or your fingers), spread the oil around the entire pan and up the edges.
About 20 minutes before you're ready to bake the pizza, put dough in skillet and flip it once to coat both sides in olive oil. Using your hands press the dough all the way to the edges of the skillet. Let it rest for 10 minutes and if it shrinks back, press to the edges again. Let rest for another 5 minutes and repeat if dough shrinks again.
Sprinkle dough with ¾ cup of shredded cheese, making sure to get close to the edges with it. Spoon sauce over the top and using a spatula or knife gently spread around. If you like a saucier pizza, use ¾ cup; otherwise just use ½ cup.
If using pepperoni, arrange it over the sauce, overlapping slices to fit more on (you can use less than 24 slices if you don't want as much). Sprinkle on remaining ¼ cup cheese and top with dried basil and red pepper flakes.
Bake for 16-22 minutes, until cheese is bubbly and crust is golden. Check after 16 minutes, using a spatula to gently lift pizza to see bottom of crust. All ovens are a bit different and everyone likes their pizza different.
Remove pizza from oven and using a spatula lift it out of the skillet and on to a heatproof cutting surface. Slice and enjoy!