Cook the pasta. Bring a large pot of salted water to a boil. Add the gluten-free pasta and cook until al dente according to package directions. Do not overcook, as the pasta will continue cooking in the sauce. Before draining, reserve about ½ cup of pasta water. Drain and set aside.
Cook the sausage. In the same pot or a large skillet, heat 2 tablespoons of olive oil over medium heat. Add the Italian sausage and cook until browned and no longer pink, breaking it into small pieces as it cooks. Remove the sausage from the pan and set aside. Carefully drain any excess grease if needed.
Sauté the aromatics. Add the remaining olive oil to the same pan over medium heat. Add the shallots and cook for 2–3 minutes until softened and fragrant. Add butter and then stir in the garlic and cook for another 1–2 minutes, just until fragrant and lightly golden. Be careful not to burn the garlic.
Make the sauce. Slowly pour in the heavy cream and stir to combine. Let the sauce gently simmer over medium-low heat until it starts to bubble slightly. Do not let it boil.
Combine everything. Add the cooked sausage back into the pan and stir until heated through. Stir in the grated Parmesan cheese until melted and smooth.
Add the pasta. Add the cooked pasta to the sauce and toss until evenly coated. Let it cook for a few minutes so the sauce thickens and clings to the pasta. If the sauce becomes too thick, add a splash of reserved pasta water to loosen it.
Finish and serve. Taste and season with salt and black pepper as needed. Serve hot with extra grated Parmesan cheese.