Melt the butter in a saucepan over medium-low heat.

Whisk in the flour and cook while stirring for 2 minutes.

Slowly whisk in the milk a little at a time. Whisk until smooth before adding more.

Bring the mixture to a simmer over medium-low heat, stirring often until it begins to thicken.

Whisk in the garlic powder and black pepper.

Remove from heat and add the shredded cheddar cheese. Stir until smooth. Taste and add a little salt if needed.