Cajun Chicken Lasagna

Name: Cajun Chicken Lasagna
Ingredients: kosher salt; 3/4 lb. lasagna noodles; 2 tbsp. extra-virgin olive oil; 1 onion, diced; 1 red bell pepper, diced; 1 yellow bell pepper, diced; 2 cloves garlic, minced; 1 lb. chicken breast, diced; Freshly ground black pepper; 3 tbsp. unsalted butter; 1 tbsp. cajun seasoning (without salt); 3 tbsp. all-purpose flour; 1/2 c. freshly grated Parmesan; 2 c. whole milk; 1/4 c. chopped fresh parsley, plus more for garnish; 16 oz. whole milk ricotta; 1 large egg; 16 oz. grated mozzarella