Cook noodles according to package.
Melt butter in skillet on medium heat. Remove from heat.
Stir in flour with a whisk, making a smooth mixture.
Return to the stovetop and continue stirring for 30 seconds until thick and bubbly.
Remove from heat and gradually stir in milk with the whisk.
Return to stovetop on medium-high heat, add Velveeta cubes and stir until melted and thickened.
Drain the macaroni pasta.
Mix sauce and macaroni together. Serve warm.