Preheat your oven to 375°F (190°C). In a medium bowl, combine the cream cheese, ricotta, parmesan, garlic powder, and oregano. Mix until smooth and well blended.

Cook the spaghetti in salted water, taking it off the heat 2 minutes early. Drain and return to the pot to keep it warm.

In a skillet over medium-high heat, add the Italian sausage and chopped onion. Brown the sausage for 8 to 10 minutes, then add minced garlic and red pepper flakes. Cook for 1 additional minute and drain excess fat.

Add the sausage mixture and marinara sauce to the pot with spaghetti. Toss everything together to coat well.

In a greased 9x13 inch dish, layer half of the pasta mixture, spread the cheese mixture over it, then add the remaining pasta mixture.

Sprinkle shredded mozzarella cheese on top. Cover with foil and bake for 30 minutes. Remove foil and broil for 2 to 3 minutes until golden.

Let the dish rest for 5 to 10 minutes before serving.