Jack
Jack is a cheese used for salt, richness, and texture. Crumble, grate, or slice it to fit the dish, and use gentle heat when melting matters.
Identity
Cheese
Cut, crumble, or grate it for the texture you want.
Cheese changes with moisture and age. Crumble, grate, slice, or melt it gently to fit the dish without losing control of salt and texture.
Wikimedia Commons
Reference image
Jack reference image.
Source: Wikimedia Commons
Substitutions
Acceptable
Grated Mild -> Jack
6 ounces (170g) grated mild or medium cheddar cheese, or any good melting cheese, such as Fontina, Gruyère, or Jack
The source lists this as an alternative in the same ingredient row.