Add the pasta to a pot of boiling water with 1 tbsp. of salt, and cook according to the package instructions, until al-dente. Drain, rinse, and set aside.
While the pasta is cooking, preahet the grill on medium-high heat. Add the chicken, shrimp seasoned with Cajun seasoning. Cook, flip occasionally, for about 10 minutes, until the chicken and shrimp are just tender and cooked through. Remove the chicken and shrimp from the grill.
in a skillet, add the bell peppers and onions. Cook for about 5 minutes, and remove the vegetables from the skillet.
Add the chicken broth and boil down until there is only 25% of the liquid left.
Stir in the Half & Half, garlic, and Parmesan cheese and stir until just creamy and smooth. Let it come to a simmer without boiling.
Stir in the vegetables, chicken, shrimp, and drained pasta, tossing until noodles are well coated in sauce.
Garnish with chopped parsley, if desired