Spicy Broccolini Pizza

Name: Spicy Broccolini Pizza
Ingredients: 1 lb. (500 g) pizza dough, store-bought or homemade; All-purpose flour for dusting; Kosher salt and freshly ground black pepper; 10 oz. (315 g) broccolini, ends trimmed, thick stalks halved lengthwise; 1 small red onion, thinly sliced; 1 or 2 jalapeño chiles, thinly sliced into rings; 2 Fresno chiles, thinly sliced into rings; 1/4 cup (2 fl. oz./60 ml) extra-virgin olive oil, plus more for drizzling; 1 1/4 cups (5 oz./155 g) grated mozzarella cheese; 1/4 cup (1 oz./30 g) grated Parmesan cheese, plus more for serving; Flaky sea salt; Red pepper flakes (optional)