01 - Preheat your oven to 375°F (190°C).
02 - Heat olive oil in a large skillet over medium-high heat. Toss shrimp with 1 tablespoon of Cajun seasoning and sauté for 2–3 minutes until just pink. Remove shrimp to a plate and set aside.
03 - In the same skillet, add butter. Sauté the chopped onion and diced bell peppers for 4–5 minutes until softened. Add the minced garlic and cook for 1 minute more.
04 - Pour in the heavy cream and bring to a gentle simmer. Reduce heat to low. Stir in 1 cup of mozzarella cheese, ¾ cup of Parmesan cheese, the remaining Cajun seasoning, salt, black pepper, and crushed red pepper flakes. Simmer for 3 minutes, stirring constantly, until the sauce is smooth and slightly thickened. Remove from heat.
05 - Assemble the lasagna in a 9x13-inch baking dish. Spread a thin layer of the prepared sauce on the bottom of the dish. Arrange 3–4 lasagna noodles over the sauce. Top with a layer of sauce, a portion of the cooked shrimp, and a sprinkle of chopped parsley. Repeat these layers, finishing with a final layer of noodles, sauce, and the remaining mozzarella and Parmesan cheeses.
06 - Cover the baking dish tightly with aluminum foil. Bake for 30 minutes. Remove the foil and continue baking for an additional 10–15 minutes, until the top is golden brown and bubbly.
07 - Allow the lasagna to rest for 10 minutes before slicing. Garnish with fresh parsley and serve warm.