Preheat the oven to 375°F. In a skillet, heat 5 tablespoons of butter over medium heat. Add the white parts of the green onions, the green and red bell peppers, onion, and celery with a pinch of salt.
Sauté until the vegetables are soft and fragrant, about 5 minutes. Next, add in the garlic, 3-4 teaspoons of Cajun seasoning (to taste), and the zest of 1 lemon. Cook, stirring constantly, until the garlic is fragrant, about 30 seconds to 1 minute.
Add in 1 pound of crawfish meat, then season with salt and black pepper to taste. Stir to warm through.
Next, add in 8 ounces of cream cheese, 2 tablespoons hot sauce (or more, to taste), 2-3 teaspoons of Worcestershire sauce, 2 teaspoons of horseradish, and 2 tablespoons of Creole mustard.
Reduce the heat to medium-low, and cook, stirring often to melt the cream cheese. Once the cream cheese is softened, begin adding in the parmesan and sharp white cheddar cheese in small handfuls, about 1.5- 2 ounces of each cheese at a time.
Keep adding the cheese in small handfuls to melt it gently, making sure to save some cheese for topping the dip before it goes in the oven. Add in some dark green parts of the green onions (reserving some for later).
Once the cheese is melted, remove it from the heat, and stir in the juice of ½ a lemon. Top with the remaining cheese and the crushed Ritz crackers. Transfer to the oven to bake. Bake until golden brown and bubbly, about 25-30 minutes.
To serve, top with more fresh parsley, green onions, and optional crawfish. Serve with more hot sauce, baguette slices, crackers, tortilla chips, veggies, or whatever you'd like! Enjoy!
Store leftovers in an airtight container in the fridge for up to 4 days. Just pop it in the microwave to warm it up when you're ready to eat it again.