Bring a large pot of salted water to boil and cook penne pasta according to package directions until al dente. Reserve ½ cup pasta water before draining.
In a large skillet over medium-high heat, crumble the Italian sausage and brown completely, breaking it into small pieces. Remove sausage and set aside.
In the same skillet with remaining drippings, cook minced garlic for 30 seconds until fragrant.
Whisk in chicken broth (or white wine) and flour, cooking for 1-2 minutes to eliminate raw flour taste.
Add diced tomatoes and bring to a simmer. Cook for 5 minutes to allow flavors to meld.
Stir in heavy cream and return cooked sausage to the skillet. Season with salt and pepper.
Add drained pasta to the skillet and toss to combine. Add pasta water if needed for desired consistency.
Remove from heat and stir in torn basil leaves and freshly grated Parmesan cheese before serving.