Preheat the oven to 400 degrees.
Cook the pasta according to the directions on the package. Drain, reserve some pasta water, then set the pasta aside.
8 cups water, 2 1/2 tsp kosher salt, 1 16 oz. box large elbow pasta
Heat the oil in a large saucepan or skillet over medium heat.
1 tbsp canola oil
Add the sausage, onion, and chopped peppers. Cook until the sausage has begun to brown and the vegetables are tender.
1 lb andouille sausage, 1 yellow onion, 4 multi colored bell peppers
Add in the garlic and cook for an additional 30 seconds. Remove the sausage and vegetables from the skillet and set them aside.
1 tbsp minced garlic
In the same skillet, melt the butter, then add the flour. Whisk together for 3 minutes.
½ cup unsalted sweet cream butter, ½ cup flour
Gradually whisk in the milk (or cream or half & half), stirring continuously. Increase the heat to a medium-high while whisking constantly for about 4 minutes or until it starts to become thick.
4 cup whole milk, half and half, or heavy cream
Add the Cajun seasoning to the roux mixture and stir.
2 tsp Cajun seasoning
Remove the skillet from the heat, then begin gradually adding the shredded cheese, whisking until the cheese is completely melted before adding more. Continue until you have a smooth and creamy cheese sauce.
8 oz shredded Cheddar cheese, 8 oz shredded pepper Jack cheese
Add the pasta, sausage, crawfish, and pepper mixture to the cheese sauce. Fold in until well combined.
½ lb crawfish meat
Transfer the mac and cheese to a large cast iron skillet or baking dish and bake for 15-20 minutes or until golden and bubbly.
Serve, and enjoy!