Bring a large pot of salted water to a boil. Cook the spaghetti according to package directions until al dente. Drain, but reserve 1 cup of the cooking water.

Heat a splash of olive oil in a large skillet or saucepan over medium heat. Add the onions and cook for about 5 minutes, until softened and translucent.

Stir in the garlic and ground beef. Cook until the beef is browned and fully cooked through.

Mix in the zucchini, mushrooms, and leeks. Cook for a few minutes until they begin to soften.

Add the tomato paste and cook briefly, about 1 minute, to remove any raw taste.

Pour in the passata, then add basil, Italian seasoning, and paprika. Stir well and let the sauce simmer on low heat for 15–20 minutes so the flavors meld together.

Taste and season with salt and black pepper as needed.

Toss the cooked spaghetti with the sauce directly in the pan. If the sauce feels too thick, add a splash of the reserved pasta water until you reach your desired consistency.

Garnish with extra fresh basil and a generous sprinkle of Parmesan cheese. Enjoy!