Bring a large pot of salted water to a rolling boil for the pasta. Dice the yellow onion and mince the garlic cloves. Remove casings from the Italian sausage if necessary.

Add the dry pasta to the boiling water and cook according to package directions until al dente. Before draining, make sure to reserve about 1 cup of the starchy pasta cooking water, then drain the pasta well.

While the pasta cooks, heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the Italian sausage, breaking it up into crumbles with a spoon, and cook until it's browned and fully cooked through, about 5-7 minutes. Drain any excess fat from the skillet and set the cooked sausage aside in a bowl.

Reduce the heat to medium. Add the diced onion to the same skillet (no need to clean it) and cook until it's softened and translucent, about 3-5 minutes. Stir in the minced garlic and cook for just another minute until fragrant, being careful not to let it burn.

Pour in the crushed tomatoes, 0.5 teaspoon of salt, and 0.25 teaspoon of freshly ground black pepper. Bring the sauce to a gentle simmer, then reduce the heat to low and let it cook for 8-10 minutes, allowing the flavors to meld and deepen.

Stir the heavy cream into the tomato sauce. Add the cooked sausage and the drained pasta back into the skillet with the sauce, tossing everything to coat evenly. If the sauce seems a bit too thick, add a splash or two of the reserved pasta cooking water until it reaches your desired consistency.

Serve immediately, garnished generously with fresh basil and freshly grated Parmesan cheese. Enjoy!