Cajun Shrimp and Sausage Pasta

large shrimp (you can either remove the tails or leave them on for a more elegant presentation, peeled and deveined)

butter (divided use)

smoked sausage such as andouille or kielbasa (cut into slices)

Cajun seasoning (or more to taste)

yellow onion (minced)

sliced bell peppers (I used red and yellow)

linguine pasta (other long pasta varieties will also work)

finely grated parmesan cheese

heavy cream

chopped parsley