Carrot Pizza with Fontina and Red Onion

Name: Carrot Pizza with Fontina and Red Onion
Ingredients: 2 tablespoons olive oil; 1/2 medium onion, chopped; 1/2 pound carrots (about 3-4 medium carrots), peeled and thinly sliced; 1/2 cup white wine; 1/2 teaspoon kosher salt; 1/4 cup mascarpone; 1/8 teaspoon cayenne pepper; 1/2 pound prepared pizza dough, room temperature; All-purpose flour (for surface); Olive oil (for brushing); 8 ounces Fontina cheese, grated (about 2 cups); 1/2 medium red onion, root intact and thinly sliced lengthwise into wedges; 1 cup (loosely packed) carrot fronds or baby arugula