In a skillet over medium-high heat add ground beef and season with kosher salt. When meat is broken up add onions and garlic. Continue to cook until the meat is browned and garlic and onions are soft. Drain any excess grease.
While the meat is cooking, boil spaghetti noodles in salted water according to package instructions.
In the pan with your ground beef, onions, and garlic. Add the diced tomatoes and zucchini. Cook for 5-8 minutes until veggies are softened. Add spinach and cook for another couple minutes, until it's lightly wilted.
Add your marinara and cottage cheese to the skillet and mix together well.
Transfer the noodles and marinara/meat/vegetable mixture into the 9x13 casserole dish. Mix together until combined. Top with mozzarella and bake for 30-35 minutes until cheese is melted and slightly browned. Let sit for a few minutes before cutting into six servings. Enjoy!