In a large skillet or pot over medium heat, add the ground beef and Italian sausage. Cook until no longer pink.

Season with salt and pepper and add the diced onion.

Cook until onion has softened, about 5 minutes.

Sprinkle in garlic powder and add the minced garlic. Cook for 1 minute, until fragrant.

Add the tomato paste and cook, stirring frequently, until it caramelizes and deepens in color, about 4–5 minutes.

Pour in the jar of marinara.

Add ¼ cup water directly to the marinara jar, swirl to rinse it out, then pour it into the pan. Stir well.

Reduce heat and let the sauce simmer while you cook the pasta.

In a separate pot, boil the spaghetti according to package directions until al dente.

Drain the pasta and add it to the sauce. Toss to combine.

Serve warm.