Preheat oven to 400°F. Lightly spray rectangle tart pan with vegetable pan spray. Roll out pizza crust to line tart pan. Press crust into base and up sides of pan. Trim away excess dough and reserve for another use. Bake 8-10 minutes.
Meanwhile, heat oil over medium-high heat in large skillet. Cook red and green peppers, onion, seasoning mix and garlic until vegetables are crisp tender, 5-8 minutes. Remove skillet from heat. Stir in chicken and salsa. Remove pizza crust from oven to cooling rack. Evenly spoon chicken mixture over pizza crust; sprinkle with cheese.
Bake 8-10 minutes or until cheese is melted and crust is golden brown. Remove from oven to cooling rack; cool 5-8 minutes. Remove from pan to serving platter. Cut into squares and serve immediately.