Creamy Cajun Shrimp Pasta

Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain. Melt butter in a large heavy skillet over medium heat. Saute red pepper and garlic for 2 minutes. Add shrimp for 1 minute on each side. Remove shrimp with a slotted spoon; set aside. Stir in flour and Cajun seasoning. Cook, stirring for 2 minutes. Gradually whisk in milk, then cook until thickened. Remove from heat, and season with parmesan cheese and lemon juice. Return shrimp to sauce, and spoon over cooked pasta.