Melt butter in a small pot over medium heat. Add chopped onion and cook until translucent. Add in flour, garlic powder, and chipotle pepper and stir until butter is absorbed into the flour. Add 1/3 cup of milk and stir until incorporated. Add the remaining milk and stirring occasionally until completely incorporated and thickened (about 5 minutes).

Meanwhile, cook macaroni elbows in a pot of water at a rolling boil until cooked to preference (al dente or otherwise). Strain and rinse under lukewarm water to get rid of the starch. Transfer back to pot and set aside.

Stir in the nutritional yeast and salt to the sauce, tasting and adjusting as necessary. For more thick and cheesy flavour, add an extra tbsp or two of nutritional yeast. Pour over cooked macaroni elbows, stir and serve immediately!