Preheat oven to 400°F. If you're using fresh dough from a pizzeria, take it out of the fridge and bring it up to room temperature before stretching it out.
Place a large, nonstick skillet over medium-high heat, add EVOO. Add the onions to the pan, season with salt and pepper and cook until caramelized, about 15-20 minutes, stirring every now and then so the onions don't burn. When caramelized, remove from heat and reserve.
Sprinkle some cornmeal or flour on the baking sheet so it doesn't stick on the bottom then roll out the dough and stretch it to make it fit the pan. Brush it with EVOO and bake for 10-15 minutes, until almost cooked through.
Spread the caramelized onions out over the dough to cover. Add the torn pieces of roast beef and cover with cheese.