Preheat your oven to 400F degrees.
Fill a Dutch Oven with salted water and boil over high heat.
Add your elbow macaroni and cook until al dente. Follow the package directions.
16 ounce package elbow macaroni
Drain your macaroni and set aside.
Return the empty Dutch Oven to the stove.
Add the olive oil and heat to medium-high heat.
1 tablespoon olive oil
Add the sausage, bell peppers, and onion to the Dutch Oven.
16 ounce package Cajun or andouille sausage, 1 green bell pepper, 1 red bell pepper, 1 white or yellow onion
Cook and stir frequently for 6-8 minutes or until tender.
Remove everything from the pot and wipe down to remove excess grease.
Reduce to medium heat.
Add in the butter and garlic and cook 1-2 minutes.
6 tablespoons salted butter, 1 teaspoon minced garlic
Whisk in the flour and cook for 2 minutes, stirring constantly.
6 tablespoons all purpose flour
Slowly add your milk, whisking well, and cook until the sauce thickens.
4 cups milk
Add the cajun spices.
2 teaspoons Cajun seasoning
Mix roughly 1 ½ cups of each cheese until melted completely.
8 ounce block cheddar cheese, 8 ounce block pepper jack cheese
Add the macaroni, sausage, and vegetables to your cheese sauce and stir until everything is well combined.
Smooth the top of the mac and cheese and add the remaining cheese. If you prefer, you can move everything to a casserole dish before topping it with cheese.
8 ounce block pepper jack cheese, 8 ounce block cheddar cheese
Put the Dutch Oven into the oven and bake for 20 minutes, or until the cheese melts on the top and the edges bubble. It should be golden brown.