01 - Cook macaroni in salted boiling water until just al dente. Drain and set aside.
02 - Melt butter in a large pot over medium heat. Add onion and carrot, cook until soft, approximately 4 minutes. Add garlic and cook for another minute.
03 - Sprinkle flour over the vegetables and stir to coat evenly. Cook for 1-2 minutes to eliminate raw flour taste.
04 - Slowly whisk in milk and vegetable broth, ensuring no lumps form. Bring mixture to a gentle simmer.
05 - Add dry mustard, salt, and pepper. Reduce heat to low setting.
06 - Stir in cheeses gradually, one handful at a time, mixing until completely melted and soup achieves smooth consistency.
07 - Add cooked macaroni to the soup. Heat gently for 2-3 minutes. Adjust seasoning to preference. Serve hot, garnished with chives or bacon bits if desired.