Preheat oven to 500°F with a rack in the center. Preheat a pizza stone on the center rack if you have one.
In a 12-inch skillet, cook bacon until crispy. Remove bacon from pan and set aside. Drain off all but 1 tablespoon fat from pan. Return pan to medium heat and add onion and garlic. Cook, stirring occasionally, until beginning to soften, about 5 minutes. Stir in cauliflower along with 1/4 cup water. Cover and cook until just tender. Sprinkle with salt and pepper.
Meanwhile, rub the olive oil over the pizza dough and stretch dough to cover a half sheet pan. Spread sauce over dough and sprinkle with mozzarella and rosemary. Spread cauliflower mixture evenly over pizza and sprinkle with pecorino. Bake for 12-15 minutes, until crust is done and cauliflower has some nice charred spots.
Sprinkle pizza with reserved bacon and some flaky sea salt and freshly ground black pepper. Drizzle with balsamic glaze. Cut into rectangles and serve right away.