Cook pasta in salted boiling water, undercooking by 1 minute. Reserve 1 cup pasta water, then drain.
Flatten the chicken breast to even thickness (about 1–1.5 cm).
Season with salt and pepper, then lightly coat with flour.
Heat olive oil in a pan over medium-high heat. Cook chicken for about 2 minutes per side or until cooked through. Set aside and cover.
In the same pan, melt butter over medium heat. Add garlic and cook gently for 1 minute (do not brown).
Add rosemary and cook for 30 seconds.
Pour in cream and bring to a gentle simmer.
Add parmesan in batches, stirring until melted and smooth.
Stir in black pepper and lemon juice.
Add ¼ cup pasta water and simmer for 2–3 minutes until slightly thickened.
Add pasta and toss gently, letting it cook for another minute.
Slice chicken and serve on top or mix into the pasta.
This Creamy Chicken Pasta Recipe is best served immediately with extra parmesan and fresh herbs.