Heat the olive oil in a medium skillet over medium-high heat. Add the shrimp and toss until firm and cooked. Remove from heat.
Place the pizza crust(s) on a baking sheet or pizza stone. Spread with the pesto. Add dollops of ricotta cheese, distributing evenly over the crust(s). Top with the cooked shrimp and tomatoes. Bake for 10-12 minutes. Top with grated Parmesan cheese, if using, and serve.