Preheat the oven to 375°F and lightly coat a 9x13-inch baking dish with non-stick spray.

Bring a large pot of salted water to a boil and cook the spaghetti until al dente. Drain, rinse with cold water, and return to the pot. Toss with half of the marinara sauce and butter (if using).

Heat olive oil in a large skillet over medium heat. Add onion and green bell pepper, and cook for 5-7 minutes until soft.

Add ground beef and cook until no longer pink; drain excess fat.

Stir in garlic, Italian seasoning, salt, black pepper, and crushed red pepper, and cook for about 1 minute until fragrant.

Add chicken broth and the remaining marinara sauce to the skillet, bring to a boil, then lower heat and simmer for 5 minutes.

In a bowl, mix mozzarella (reserve 1 cup), cottage cheese, ricotta, cream cheese, and parmesan until smooth and creamy.

Stir mozzarella into meat sauce and another handful into spaghetti mixture.

Spread spaghetti evenly in the prepared baking dish.

Layer cheese mixture over spaghetti, followed by meat sauce. Top with reserved mozzarella.

Bake for 20-25 minutes until bubbly and golden. Let cool for 5-10 minutes before serving.