Bring a large pot of salted water to a boil. Cook the pasta according to the package directions until al dente. Reserve about 1/2 cup of pasta water, then drain.
Heat the olive oil in a large skillet over medium heat. Add the beef sausage pieces and cook until browned and lightly crisp on the outside. Transfer them to a plate.
Reduce the heat and add the butter to the same skillet. Once melted, add the minced garlic and sauté for about 30 seconds, until fragrant.
Pour in the heavy cream and gently simmer over low heat for 2–3 minutes. Avoid bringing the cream to a rapid boil.
Stir in the Parmesan cheese until melted and the sauce becomes smooth and creamy. Season with salt and black pepper.
Add the cooked pasta and sausage bites to the skillet. Toss gently until everything is evenly coated. If the sauce is too thick, add a small splash of reserved pasta water.
Serve the Garlic Butter Sausage Bites and creamy Parmesan pasta immediately, topped with fresh parsley and extra Parmesan if desired.