Melt 2 tablespoons of unsalted butter in a medium saucepan over medium heat. Add 2 tablespoons of all-purpose flour and stir continuously for 1-2 minutes until golden and bubbly to form a roux.
Slowly whisk in 1 cup of whole milk until the mixture is smooth and starts to thicken, about 3-5 minutes.
Reduce heat to low and gradually stir in 1 1/2 cups of grated Cheddar cheese until fully melted and smooth.
Add 1/4 teaspoon onion powder, 1/8 teaspoon garlic powder, 1/4 teaspoon salt, and 1/4 teaspoon pepper. Optionally add cayenne pepper or smoked paprika.
Taste and adjust seasoning as necessary, adding more cheese if desired.
Serve your Cheddar Cheese Sauce over nachos, pasta, or veggies!