Slice each chicken breast horizontally into 3 thinner pieces using a sharp knife. Sprinkle each chicken piece with garlic salt and Italian seasoning on both sides.

Heat olive oil in a large skillet over medium-high heat. Add chicken and cook until golden and cooked through, about 2 minutes per side. Remove onto a plate.

Add milk and garlic to the skillet. Bring to a simmer and add fettuccine. Cook, stirring every 30 seconds to prevent sticking until pasta has softened, about 3 minutes. Reduce heat to medium and cook, stirring every couple of minutes, 6 to 7 minutes more. Stir in cream and Parmesan cheese. Simmer, stirring occasionally, until sauce has thickened and pasta is cooked, about 2 more minutes.

Serve immediately and garnish with additional Parmesan cheese if desired.