Cook the pasta to al dente according to the package directions and set aside.
Sprinkle the crawfish tails with Creole seasoning and set them aside.
Prepare the jalapeno pepper by slicing in half lengthwise and removing the seeds and membrane. Finely chop.
Grate the cheeses, measure the other ingredients and set them aside. Prepare a casserole dish by spreading softened butter on the inside.
Preheat the oven to 350 degrees Fahrenheit.
Start with a cold Dutch oven. Add the heavy cream, melted butter and eggs to the Dutch oven off the heat. Whisk together until all are combined thoroughly.
When the cream, eggs and butter are completely combined, move the Dutch oven over medium heat and slowly warm the cream mixture, stirring or whisking constantly until a slight simmer develops.
Add the Pepper Jack Cheese and 2 cups of the Cheddar Cheese (reserve the remaining cheese for the top) and stir to combine the cheese into the cream sauce.
Continue to stir as the cheese melts.
Add the Creole seasoning, kosher salt, white peppers, dry mustard, chopped pimentos and chopped jalapenos (if using). Mix together thoroughly.
Add the crawfish tails and stir until evenly distributed throughout the cheese sauce.
Simmer the cheese sauce on low heat for a minute or two.
Add about half of the cooked pasta and combine thoroughly. Mix in more pasta, a little at a time, until all of the pasta is heavily coated with cheese sauce. Be careful not to add too much pasta or there won’t be enough cheese sauce to coat it all.
Turn the macaroni and cheese mixture into a baking casserole dish that has been prepared by coating the insides with softened butter.
Spread the remaining Cheddar Cheese evenly on top and sprinkle about 2 tablespoons of breadcrumbs (if using) evenly on top, then place small pats of butter on top of that.
Place the casserole, uncovered, in the preheated oven for approximately 20 minutes or until the cheese topping is starting to brown.
Remove the casserole from the oven and let it sit for about 5 minutes, then serve.
Notes
Read my article Crawfish Mac and Cheese for step-by-step photos and more hints and tips.Use only Louisiana crawfish tails. This recipe is a great way to use leftover crawfish from your boil.If you want less heat, leave out the jalapeno pepper and substitute Monterey Jack Cheese for the Pepper Jack.Cheddar and Jack cheese blend into a great flavor but experiment with other types of cheese for an almost endless variety of flavors.Leftover macaroni and cheese can be kept air-tight in the refrigerator for 3 to 5 days or the freezer for up to 3 months; reheat in single-serving sizes in the microwave or reheat the entire casserole (after defrosting overnight in the fridge) at 350 degrees until the internal temperature is 165 degrees.This casserole can be made in advance and frozen either before or after baking. Before baking, defrost in the refrigerator overnight, then bake according to the recipe instructions. If after baking; defrost and bake at 350 degrees, covered in aluminum foil until the internal temperature is 165 degrees Fahrenheit.If substituting, use a hearty, thick pasta so the sauce has a place to land. Some suggestions: bowtie, rotini, long macaroni, or fettuccini.