Melt the butter: In a small saucepan, melt butter over medium heat until it begins to bubble slightly. Be careful not to brown it—this step helps create a smooth base for your cheese spread.

Add flour: Whisk in the flour to create a roux. Continue whisking for about 1–2 minutes until it forms a smooth paste and loses its raw flour taste. The roux will thicken and become slightly golden in color.

Incorporate milk: Gradually pour in the warm milk while whisking continuously to avoid lumps. Continue stirring until the mixture becomes creamy and starts to thicken—this takes around 3–5 minutes.

Add cheese: Lower the heat to low and slowly add the cheddar, American, and cream cheese. Stir constantly until all the cheese has melted and the sauce looks smooth and glossy.

Season: Mix in mustard powder, paprika, garlic powder, salt, and pepper. Keep stirring to fully blend the flavors. If you want a thinner consistency, whisk in a splash of warm milk until you reach your desired texture.

Finish and serve: Remove from heat and let it rest for 1–2 minutes to slightly thicken. Transfer the cheese spread into a small serving bowl. It will firm up a bit as it cools, creating that signature Whataburger-style creamy, spreadable texture.