Cook penne pasta according to package directions. Reserve ½ cup pasta water, then drain.
Season chicken with salt and pepper.
Heat oil and 1 tablespoon butter in a skillet. Cook chicken 4–5 minutes per side until fully cooked. Remove and set aside.
Reduce heat and add remaining butter. Sauté garlic until golden.
Add rosemary, then pour in chicken broth while scraping the pan.
Stir in cream and simmer for 4 minutes.
Slice chicken and return to sauce. Simmer for 5 minutes.
Add pasta and toss. Use reserved pasta water to adjust consistency.
Serve Creamy Garlic Chicken Pasta topped with parmesan cheese.