Preheat the oven to 375°F (190°C). In a large skillet over medium-high heat, add two tablespoons of butter and melt until browned and frothy. Add the onions and red peppers, and sauté until tender. Stir in the minced garlic, whole grain mustard, and Cajun spices.
Add the crawfish tails and green onions and stir until completely incorporated with the onions and peppers. Season with Louisiana hot sauce, lemon juice, salt, and pepper, to taste. Mix in the mozzarella and Parmesan cheeses. Remove from heat. While it cools, mix in the cream cheese until creamy.
Cut off the tops of each roll, about 1/4 inch of crust. Use your fingers to remove the bread from within each roll, leaving about a 1/2 inch of crust remaining. Use a spatula to spread mayonnaise onto the inside and outside of each roll and crust top.
Spoon the crawfish mixture into each roll. Top the rolls and crusts with additional mozzarella, Parmesan cheese, and fresh parsley. Bake for 15-20 minutes or until the rolls are heated through and the cheeses have melted on top.
Garnish with additional mozzarella, Parmesan, chopped green onions, and fresh parsley. Let the good times roll! Enjoy!