Preheat the oven to 375. Lightly grease a 9x13 pan and set aside.
In a large skillet cook, crumble and drain the ground beef. Add the salsa, tomato sauce and taco seasoning and stir to combine. Simmer on low heat 10-15 minutes.
In a separate bowl mix the cottage cheese, egg and oregano and mix well. Set aside.
In a lightly greased 9x13 baking dish, begin your layers starting with tortillas on the bottom. It's okay if they overlap. Next spread 1/3 of the meat mixture, 1/2 of the cottage cheese, and 1/3 of the shredded cheese. Dot with a few black olives. Repeat tortillas, sauce and cheeses for a second layer, using the last half of the cottage cheese mixture.Top with a third layer of tortillas and spread over the last third of the sauce. Do your best to cover any exposed tortillas or they get really crispy.
Cover with remaining cheese and black olives and bake uncovered for 30 to 35 minutes until the cheese is bubbling and brown. Remove from the oven and allow to sit for 10 minutes before cutting.
Notes
Serve with tortilla chips. Make two 8x8 pans and freeze one for another night. Thaw overnight in the fridge before baking.