Prep the oven and pan: Heat the oven to 375°F (190°C). Lightly oil a 9x13-inch baking dish.
Cook the noodles: If using regular noodles, boil in salted water until very al dente (about 2 minutes less than the package says).
Drain and lay flat on a sheet pan to prevent sticking. Skip this if using no-boil.
Brown the meat: Heat olive oil in a large skillet over medium. Add onion and cook 3–4 minutes until soft.
Stir in garlic for 30 seconds, then add ground turkey or beef. Cook, breaking up with a spoon, until browned and no pink remains. Season with salt, pepper, Italian seasoning, and red pepper flakes.
Make the sauce: Stir in crushed tomatoes and tomato paste.
Simmer 10 minutes to thicken. Taste and adjust salt and pepper. You want a slightly bold, savory sauce—it’ll mellow in the oven.
Mix the cheese layer: In a bowl, whisk cottage cheese with the egg and Parmesan.
For a smoother texture, blend the cottage cheese first. Stir in a pinch of salt and pepper. If using spinach, fold it in now (it will wilt in the oven).
Layer the lasagna: Spread 1 cup of sauce on the bottom of the dish.
Add a layer of noodles. Spoon on half the cottage cheese mixture and spread gently. Sprinkle with 2/3 cup mozzarella.
Add a second layer of sauce. Repeat: noodles, remaining cottage cheese, mozzarella, more sauce. Finish with a final layer of noodles, the rest of the sauce, and the remaining mozzarella on top.
Bake covered, then uncovered: Cover tightly with foil (tent slightly so cheese doesn’t stick).
Bake 25 minutes. Remove foil and bake another 15–20 minutes, until bubbling and golden in spots.
Rest before slicing: Let it sit 10–15 minutes. This step helps the layers set and gives you clean slices.
Finish and serve: Scatter chopped basil or parsley over the top.
Slice and serve warm.