Cheesy Chicken Enchiladas

No-Stick Cooking Spray
2 cans (8 oz each)Tomato Sauce
1 cup water
1-2 teaspoon(s) Chili Powder
3 cups shredded cooked chicken
1 medium onion, chopped
1 tablespoon water
12 white corn tortillas (6 inch)
2 tablespoons shredded Cheddar cheese
1-1/2 cups shredded Cheddar cheese

Preheat oven to 400°F. Spray 13x9-inch baking dish with cooking spray; set aside.
Combine tomato sauce, 1 cup water and the chili powder in medium saucepan. Bring to a boil over medium-high heat. Reduce heat to low; simmer 10 minutes, stirring occasionally. Meanwhile, mix chicken, onions and remaining 1 tablespoon water in large nonstick skillet. Cook over medium-high heat 3 to 4 minutes, or until onions are tender, stirring occasionally.
Wrap tortillas in damp paper towels; place on microwavable plate. Microwave on HIGH 1 minute, or until tortillas are warmed and softened. Top each tortilla with 2 tablespoons cheese and about 1/4 cup of the chicken mixture; roll up. Place, seam-sides down, in prepared baking dish. Cover evenly with the tomato sauce mixture; sprinkle with remaining 1-1/2 cups cheese. Cover with aluminum foil.
Bake 30 minutes, or until cheese is melted and sauce is bubbling.