Cook the pasta according to package instructions.
Season the shrimp with about 1/2 tbsp of the cajun seasoning and set aside.
In a large skillet or Dutch oven heat the olive oil. Add the shrimp and cook on both sides until it turns pink, about 2 min per side, could be less depending on the size of your shrimp. Remove the shrimp from the pot and set aside.
Add the chicken and sausage to the pot, and sprinkle about 1 tbsp of the cajun seasoning over the chicken. Stir everything together and cook until the chicken is no longer pink and is cooked through, about 5 minutes.
Add the onion, celery and garlic to the skillet and cook until the onion becomes translucent, about 3 minutes.
Add all the peppers and sprinkle the remaining 1/2 tbsp of cajun seasoning over the peppers, stir well and cook for another 3 minutes.
Add the chicken broth and heavy cream to the skillet, stir and season with salt and pepper if needed. Add the shrimp back to the pot. Bring the sauce to a boil, then add the cooked pasta and about 1/2 cup of the shredded Fontina cheese. Stir everything together.
Remove from heat, then garnish with the remaining Fontina cheese, green onions and parsley. The pasta will continue to soak up the sauce.
Serve immediately. Refrigerate leftover for up to 3 days.