Cook the macaroni according to package instructions until al dente, then drain.
In a large skillet, heat olive oil over medium heat and add the asparagus. Sauté for about 5 minutes until tender-crisp.
Add minced garlic to the skillet and sauté for another minute until fragrant.
Pour the milk into the skillet, then bring it to a gentle simmer.
Whisk in the grated cheddar, mozzarella, and Parmesan cheese until fully melted and smooth, creating the cheese sauce.
Stir in the Dijon mustard and season with salt and pepper to taste.
Add the cooked macaroni and sautéed asparagus to the cheese sauce, mixing well to combine.
Transfer the mixture to a baking dish and top with extra cheese if desired, then bake in a preheated oven at 180°C (350°F) for 20-25 minutes until bubbly and golden.