Start by bringing a large pot of salted water to a rolling boil over high heat. Add the fusilli pasta and cook it according to package instructions until al dente, usually about 8-10 minutes. Before draining, reserve ½ cup of the pasta water aside.

While the pasta is cooking, melt a tablespoon of unsalted butter in a skillet over medium heat. Season the boneless, skinless chicken breasts with salt and pepper, then sear them until golden brown and cooked through, about 3-4 minutes per side.

In the same skillet, lower the heat and add the remaining tablespoon of butter. Once melted, sauté the minced garlic and optional red pepper flakes until fragrant, about 1-2 minutes.

Pour in the chicken broth, scraping the browned bits from the bottom of the skillet. Add the heavy cream and Italian seasoning, stirring well. Simmer for 2-3 minutes to thicken slightly.

Reduce heat to low and gradually stir in the grated Parmesan until melted and combined.

Return the cooked chicken to the skillet, along with the drained pasta. Toss everything together to coat in the creamy sauce, using reserved pasta water to adjust consistency as needed.

Season with additional salt and black pepper, garnish with parsley, and serve immediately.