Cut tortillas into wedges or tear into strips and fry them. Saute onions in oil for 5 min. (A non-stick or cast iron skillet that's ovenproof is ideal for this). Then, add the fried tortilla pieces, chili powder, garlic, cumin and salt and toss until the tortilla pieces are wilted. Puree cottage cheese and tomatoes in blender until smooth and stir gently into tortilla pieces. Then sprinkle with grated authentic Oaxaca cheese.
Bake at 350 for about 20 min.