01 - Melt butter in a medium saucepan over medium heat. Add flour and whisk constantly for 1 minute to form a roux, taking care not to let it brown.
02 - Gradually whisk in the milk. Cook, stirring frequently, until mixture thickens and just reaches a simmer, approximately 2 to 3 minutes.
03 - Reduce heat to low. Add Dijon mustard, hot sauce, garlic powder, cayenne, salt, and pepper. Stir until fully incorporated.
04 - Add grated cheddar cheese a handful at a time, whisking until smooth and completely melted before adding more. Continue until all cheese is incorporated.
05 - Once sauce is smooth and all cheese is melted, taste and adjust seasoning as needed. Serve immediately while hot.