In a medium bowl, combine peeled and deveined shrimp with olive oil and Cajun seasoning, ensuring the shrimp are well-coated. Allow the shrimp to marinate for about 10 minutes.

Bring a large pot of salted water to a boil, then add the fettuccini. Cook according to package instructions until al dente, usually 8-10 minutes. Drain and return to the pot, keeping warm.

In a large frying pan, melt the butter over medium heat. Add sliced mushrooms and shallots, sautéing for 5-7 minutes until tender and golden. Remove from the pan and set aside.

In the same pan, add the marinated shrimp and cook for 2-3 minutes per side, or until pink and opaque. Transfer to a plate.

Pour 1 cup of chicken broth into the pan, bring to a boil and reduce until about ¼ cup remains. Mix sour cream and cornstarch with 1 cup of chicken broth; incorporate into reduced broth, stirring until thickened, about 1 minute.

Return sautéed vegetables, cooked shrimp, roasted red bell peppers, and capers to the sauce. Heat through for an additional 2-3 minutes, seasoning with salt and pepper to taste.

Spoon the Blackened Shrimp Stroganoff over prepared fettuccini in serving bowls. Enjoy immediately with a side salad if desired.