Heat oven to 350°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. In 12-inch nonstick skillet, cook beef and onion over medium-high heat 5 to 7 minutes, stirring occasionally, until beef is brown.
Stir in spinach; cook, stirring frequently, until thawed. Stir in green chiles, cumin, garlic-pepper blend, sour cream and 1 cup of the cheese.
Spread about 1 teaspoon enchilada sauce on each tortilla. Top each with about 1/2 cup beef mixture. Roll up tortillas; place seam sides down in baking dish. In small bowl, mix remaining enchilada sauce and the salsa; spoon over enchiladas. Sprinkle with remaining 1 cup cheese.
Spray sheet of foil with cooking spray; cover baking dish with foil. Bake 40 to 45 minutes or until thoroughly heated.