Cook fettuccine in salted boiling water until al dente; reserve ½ cup of pasta water before draining.

Season steak strips with Cajun seasoning generously.

Heat olive oil in a large skillet over medium-high heat. Sear steak for about 3-4 minutes until browned; remove and set aside.

In the same skillet, sauté onions and bell peppers for about five minutes until softened.

Reduce heat to medium-low; add heavy cream and scrape up any brown bits from the pan. Stir in Parmesan cheese until melted; adjust thickness with reserved pasta water if necessary.

Return cooked fettuccine and seared steak to the skillet, tossing until well coated and heated through.