Put rack on lowest level, and heat oven to 425°F. Spray a 16-inch round pizza pan lightly with cooking spray.
Boil peas until tender, 2 to 5 minutes. (Alternatively, you can use thawed frozen peas, in which case you don't need to cook them.)
Put peas, garlic, pine nuts, Parmesan, and salt in a food processor. Process until ingredients are finely chopped. While processor is on, slowly add 3 Tbs. olive oil in a thin stream until it forms the pesto.
Heat 2 tsp. olive oil in a medium skillet over medium-high heat. Add sausage and sauté, breaking up, until cooked through and lightly browned, 7 to 10 minutes. Set aside.
Stretch dough into a large circle and transfer to pizza pan. Spread pea pesto on top of dough to within 1 inch of the edge. Scatter the cooked sausage, tomatoes, and mozzarella over the pesto.
Bake for 15 to 18 minutes, until crust is golden brown. If desired, garnish with fresh basil right before serving.