Heat oven to 350. Spray a 2-1/2-quart casserole dish w/ cooking spray. In lg skillet, over med-high heat, cook ground turkey until browned.
Remove skillet from heat. Stir in tomato sauce, onion, taco seasoning and garlic powder. In bowl, combine sour cream and cottage cheese.
Place 1/2 the tortilla chips in bottom of casserole dish. Top w/ 1/2 the ground turkey mix. Top turkey ix w/ 1/2 the sour cream mix. Sprinkle w/ 1/2 the cheese. Repeat layers. Bake, uncovered 30 mins or until cheese is melted and bubbly.