Preheat your oven to 475°F (245°C). If you have a pizza stone, place it in the oven to heat up. If not, a sturdy baking sheet works just fine.
While the oven heats, prepare the toppings. Slice the bell pepper into thin strips, and slice the red onion. If your sausage isn’t pre-cooked, cook it in a skillet until lightly browned on the edges. You want it flavorful but not dry.
Roll out the dough on a lightly floured surface to a round or rectangle shape that fits your pan. Transfer to a parchment-lined sheet or a preheated pizza stone. Brush a little olive oil along the edges to help the crust crisp up.
Spread the pizza sauce evenly over the dough, leaving a small border for the crust. Scatter half of the mozzarella across the sauce, then add the spicy sausage slices, bell pepper, and red onion.
Drizzle another tablespoon of olive oil over the toppings and sprinkle with crushed red pepper flakes. Season with a pinch of salt and pepper to taste.
Top with the remaining mozzarella. Slide the pizza into the oven. Bake for 12–15 minutes, until the crust is golden and the cheese is bubbly and lightly browned.
If you like a crisper crust, switch to the broil setting for the last 60 seconds, watching closely so nothing burns.
Remove from the oven and let the pizza rest for a few minutes. Slice, garnish with fresh basil or parsley if using, and serve hot.