Prepare pasta according to package directions. Peel and devein shrimp. Set aside.
In a medium bowl, combine shallots, garlic, red pepper flakes, and olive oil. Add shrimp and marinate in fridge for 15 minutes.
Heat a cast iron pan over medium-high heat with 4 tablespoons butter. Add marinated shrimp, including remaining marinade, and sear for 1-2 minutes on each side or until cooked through. Set shrimp aside.
Reduce heat to medium. Add white wine, chicken broth, and lemon juice to the pan, using a spatula to deglaze it. Bring to a simmer and reduce for 10 minutes or until about 1 1/2 cups of liquid remain, adding salt and pepper as desired.
Stir in pasta, parsley, and shrimp to reheat. Add remaining butter, and serve with grated parmesan and additional parsley for garnish.
