1. Cook pasta according to package instructions. Reserve 1/2 cup of pasta water, then drain and set aside.
2. Heat olive oil in a large skillet over medium-high heat. Add shrimp and cook for 2-3 minutes per side, until pink and cooked through. Remove and set aside.
3. In the same skillet, add sausage slices and cook until browned, about 3-4 minutes. Remove and set aside with the shrimp.
4. Reduce the heat to medium and melt the butter in the skillet. Add garlic and red pepper flakes (if using), cooking for about 1 minute until fragrant.
5. Stir in the chicken broth and reserved pasta water, then simmer for 2 minutes.
6. Add the cooked pasta, shrimp, and sausage back into the skillet. Toss everything together until well combined and heated through.
7. Sprinkle with Parmesan cheese and garnish with fresh parsley. Serve immediately.

Pro Tip: For added zest, squeeze a little fresh lemon juice over the dish before serving!