Cook pasta according to package directions. Drain and set aside. Season chicken generously on both sides with salt, pepper, and garlic salt. Then dredge chicken in flour until coated on all sides.
Heat 2 tablespoons butter in a large skillet over medium to medium-high heat. When butter is hot and starts to turn brown, add the chicken and cook on each side, flipping once, until golden brown and chicken is cooked through, about 3-5 minutes per side. Remove the chicken to a plate and cover with foil to keep warm.
In the same skillet, add the remaining 4 tablespoons butter. When melted and foamy, add the garlic and stir until fragrant, about 30 seconds. Add the cream and bring to a simmer. Add the lemon juice and zest and whisk to combine. Add the parmesan cheese and whisk until smooth and melted.
Plate the pasta and top with chicken and sauce. Garnish with extra parmesan cheese and parsley if desired. Serve and enjoy!!