For the best mac and cheese, you want to choose flavorful cheeses that easily melt into a creamy consistency. I like to use a combination of two types of cheese for a more complex flavor profile. Sharp cheddar cheese adds a sharp, pungent flavor and melts very well while a little Velveeta adds classic flavor and a unique creaminess you just don't get from other cheeses. This is simple, uncomplicated comfort food at its best. However, if you don't want to use processed cheese, you can substitute another good melting cheese like Havarti or Gruyere.