Marinate the shrimp with lemon juice, 1 tbsp of cajun seasoning, pinch of salt and pepper.
Cook the fettuccine pasta in a pot until al dente. Then drain.
Melt the butter, then cook the shrimp until cooked and reddish in color. Set aside.
Melt the butter and chopped garlic and onion, saute until fragrant. Add diced tomatoes and saute again.
Pour in the cream, 2 tbsp of Cajun seasoning, and Parmesan cheese. Then cook until the sauce thickens.
Add the shrimp and pasta, seasoning with pinch of salt and pepper. Stir until well mixed. Then garnish with parsley.