Roll out dough to a 12-inch circle. Press dough into bottom and 1 inch up sides of a well-seasoned 10-inch cast-iron skillet. Fold edges of the dough under; crimp.
Spread ricotta cheese in bottom of crust; top with bacon, mozzarella cheese, and pepper. Place skillet over high heat; cook 3 minutes.
Transfer skillet to oven. Bake at 450 degrees for 18 minutes or until crust is lightly browned and cheese melts.
While the pizza cooks, heat a large skillet over medium-high heat. Coat pan with cooking spray. Add spinach. Cook 1 minute or until spinach wilts, turning often with tongs. Remove spinach from pan; drain and squeeze out excess liquid. Top pizza with spinach. Cut the pizza into 8 wedges.