Toss shrimp with olive oil and Cajun seasoning, then set aside.

Cook fettuccini in salted boiling water until al dente, drain, and reserve a little pasta water.

Sauté mushrooms and shallots in butter until tender, then remove.

Cook shrimp in the same pan until pink and lightly charred, then set aside.

Reduce chicken broth in the pan, then stir in sour cream mixture and cook until thickened.

Return shrimp, mushrooms, roasted red peppers, and capers to the pan and heat through.

Serve the creamy sauce over warm fettuccini.