Cook pasta according to package directions.
In a medium bowl, season chicken with a few pinches of salt, tbsp. of Old Bay and tbsp. of garlic powder. In another small bowl, season shrimp with 1 tbsp of Old Bay and tbsp. of garlic powder.
In a large skillet, heat 2 tbsp of oil over medium high heat. Cook sausage for 2 minutes on each side. Remove and set aside, covered. Add a small amount of oil to same skillet, and cook chicken pieces for 3 minutes on each side. Remove and set aside, covered. Reduce heat to medium, add a little more oil and cook shrimp for 2 minutes on each side. Remove and set aside, covered.
In the same skillet, add butter. Once butter is melted, add onion and bell pepper. Cook until tender, about 3 minutes, stirring occasionally. Add garlic and cook an additional 3 minutes. Stir in 2 tbsp of Old Bay, and mix thoroughly. Stir in tomato paste, and mix thoroughly.
Add chicken broth, heavy cream, white wine and lemon juice. Bring to a simmer and cook for 7 minutes, stirring occasionally. Stir in crushed red pepper flakes and simmer for additional 5 minutes or until sauce has thickened.
Toss cooked pasta in sauce, and top with chicken, sausage, shrimp and parmesan cheese. Topping with fresh parsley is optional.