Marinate the shrimp by combining with olive oil and Cajun seasoning. Allow to sit for 15 minutes.

Cook the fettuccini in boiling salted water according to package instructions for about 8-10 minutes. Drain and set aside.

Sauté mushrooms and shallots in butter over medium heat for 5-7 minutes until tender.

Blacken the marinated shrimp in the same pan for 2-3 minutes on each side until fully cooked.

Add chicken broth to the pan, scraping the bottom. Bring to a boil and reduce to a simmer for 2-3 minutes.

Mix sour cream and cornstarch in a small bowl, then whisk into the broth mixture until thickened.

Return shrimp, mushrooms, red bell peppers, and capers to the pan, stir and heat for 2-3 minutes.

Serve the shrimp mixture over cooked fettuccini, garnishing with fresh herbs if desired.