Preheat the oven to 450 degrees F. Position racks in the upper and lower thirds of the oven.
Divide the pizza dough into 4 equal pieces. Dust a counter with some flour and roll each piece into a 1/4-inch-thick round, dusting the dough with flour as needed to prevent sticking. Place 2 dough rounds on each of 2 rimmed baking sheets. Brush the dough with half of the olive oil. Dot each round evenly with the ricotta and torn mozzarella. Sprinkle the tomatoes over the cheeses and season with the salt. Top with the fennel and a drizzle of the remaining olive oil. Bake for 20 minutes, rotating the baking sheets halfway through.
After 20 minutes, remove the baking sheets from the oven and sprinkle the pizzette evenly with the Parmesan. Turn the broiler to high and place one baking sheet under the broiler until the Parmesan is melted and browned, about 3 minutes. Remove and repeat with the remaining baking sheet. Sprinkle with the fennel fronds and serve.