Prepare all ingredients by measuring and chopping as needed.
Heat a large skillet over medium heat and add olive oil. Cook the Italian sausage for 5-7 minutes until browned.
Add minced garlic and sauté for 1-2 minutes until fragrant. Optionally, add red pepper flakes.
Stir in diced tomatoes and let simmer for 3-4 minutes.
Cook penne pasta according to package instructions until al dente, then drain.
Reduce heat to low, add heavy cream and Parmesan cheese, stirring until melted. Season with salt and pepper.
Add cooked penne pasta to the skillet and toss everything together. Cook for an additional 2-3 minutes until heated through.