Cook the Pasta: Bring a large pot of salted water to a rolling boil over high heat. Add fettuccine or linguine and cook according to package instructions until al dente, about 8-10 minutes. Reserve ½ cup of pasta water, then drain the pasta and set aside.

Sauté the Vegetables: In a large skillet, melt butter and heat olive oil over medium heat. Add chopped onion and diced red bell pepper. Sauté for 3-4 minutes until softened.

Add Aromatics and Spices: Stir in minced garlic, Cajun seasoning, smoked paprika, and crushed red pepper flakes. Cook for an additional 1-2 minutes.

Create the Sauce Base: Pour in heavy cream and chicken broth, stir well, and bring to a gentle simmer over medium-low heat for about 3-5 minutes.

Incorporate Cheese and Lemon: Add grated Parmesan cheese and lemon juice to the sauce, stirring until smooth. Let thicken for another 5-7 minutes.

Fold in the Crab: Gently fold in lump crab meat and let it warm in the sauce for 2-3 minutes.

Combine Pasta and Sauce: Add drained pasta to the skillet and toss gently to coat, adding reserved pasta water if necessary.

Serve and Garnish: Plate the pasta and garnish with fresh parsley and additional Parmesan cheese. Serve immediately.