Preheat and prep: Heat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
Cook the meat: In a large skillet over medium heat, warm olive oil if needed.
Add onion and cook 3–4 minutes until softened. Stir in garlic for 30 seconds. Add ground beef or turkey, season with salt and pepper, and cook until browned.
Drain excess fat if necessary.
Sauce it up: Pour in marinara, Italian seasoning, and red pepper flakes. Simmer 5–7 minutes to thicken slightly. Taste and adjust salt and pepper.
Remove from heat.
Mix the cottage cheese layer: In a bowl, combine cottage cheese, egg, Parmesan, a pinch of salt, and 1 cup of mozzarella. Stir until evenly mixed. If using spinach, fold it in now.
Layer 1: Spread a thin layer of the meat sauce on the bottom of the baking dish.
Place a single layer of no-boil noodles on top, slightly overlapping if needed.
Layer 2: Spoon half of the cottage cheese mixture over the noodles and spread gently to the edges.
Layer 3: Add a generous layer of meat sauce.
Repeat: Add another layer of noodles, the remaining cottage cheese mixture, and more sauce. Finish with a final layer of noodles and the rest of the sauce on top.
Cheese top: Sprinkle the remaining 1 cup of mozzarella over everything. Add a little extra Parmesan if you like a crispier top.
Cover and bake: Cover the dish loosely with foil (tent it so it doesn’t stick to the cheese).
Bake for 25 minutes.
Uncover and finish: Remove foil and bake another 15–20 minutes, until the top is bubbly and golden around the edges.
Rest and serve: Let the lasagna rest for 10–15 minutes before slicing. Garnish with chopped basil or parsley and serve warm.