Bring a large pot of salted water to a boil. Add the macaroni and cook until just shy of al dente -- it’ll finish cooking in the sauce. Drain and set aside. Drizzle with oil and stir to prevent sticking. Allow to cool.

Heat the oil in a large pot or Dutch oven over medium heat. Add the andouille, onion, and bell pepper. Cook 3-4 minutes, stirring a bit, to brown the meat and soften the vegetables, then add garlic and cook for 1 minute. Remove to a plate and set aside. Wipe out the pot if needed.

Melt the butter in the same pot over medium heat. Whisk in the flour to form a smooth paste and cook 1 minute, stirring.

Slowly whisk in the warm milk, a little at a time, until smooth and lump-free. Cook, whisking, until the sauce thickens just enough to lightly coat the spoon, a few minutes.

Stir in the Cajun seasoning, salt, and cracked pepper and cook 30 seconds, stirring. Remove from heat and stir in most of the cheddar and pepperjack cheese, reserving a small handful of each for topping. Stir until smooth and glossy.

Add the drained pasta to the sauce and stir to coat evenly. Stir in the cooked andouille and vegetables. Serve right away for a creamy stovetop version (topped with the reserved cheese), or bake it for a bubbly/cheesy mac and cheese with an optional crisp, golden crust.

Preheat the oven to 350°F. Butter an 8×8 or 9×13 baking dish. Spread the mac and cheese evenly in the dish and top with the reserved cheese.

Mix the panko, melted butter, and Parmesan together, then sprinkle over the top. Bake for 25-30 minutes, until golden and bubbling around the edges. Let it sit 5 minutes before serving so the sauce settles and thickens slightly.