Preheat the oven to 350 degrees F and grease a 9x13 pan with nonstick spray.
Pour a 16-ounce container of cottage cheese into a fine-mesh strainer and let drain over a large bowl while browning the beef.
In a large non-stick skillet, brown the ground beef with the minced onions, breaking up as the meat cooks.
Once the meat is browned, drain off excess fat and return to skillet. Add in the garlic, cumin, chili powder, salt, and diced tomatoes, and bring to a simmer. Lower heat to medium-low and simmer for 5 minutes, or until the liquid is reduced by at least half.
In a medium mixing bowl, mix together the drained cottage cheese, the egg, and Monterey Jack cheese together until combined.
Place 6 tortillas on the bottom and sides of the pan, forming a crust, overlapping slightly.
Pour beef mixture over tortillas and cover with an additional layer of tortillas, just to cover the top of the meat mixture.
Top the tortillas with the cottage cheese mixture and then sprinkle with cheddar cheese.
Bake for 30-40 minutes at 350 degrees, or until the cheese is melted and bubbly.
Rest for 10-20 minutes before slicing and serving with desired toppings.
Prep-Ahead Instructions: To prepare in advance, assemble as directed, cover with foil, and refrigerate it for up to 24 hours. To bake, uncover, and cook for 45-55 minutes at 350 degrees F.Storage: Leftovers can be stored in an airtight container in the refrigerator for up to 3 days.Meat: Feel free to use ground chicken or turkey in place of the beef. Cheese: If the Pepper Jack cheese is too spicy, use Monterey Jack in its place.