Ingredients :

• The potatoes — Choose Charlotte or Monalisa, waxy varieties. Bintje are for mash—they will turn into a gluey puree here and ruin the layers. Slice them 3-4 mm thick, using a mandoline if you have one, otherwise with a knife taking your time.
• The ground beef — At least 15% fat, 20% is even better for this type of dish. Lean beef releases liquid during cooking and dries out on the surface. The fat provides the flavor here.
• Condensed mushroom soup — Undiluted, straight from the can. This is what creates the creamy texture without having to make a bechamel. It liquefies on its own with the juices the potatoes release during cooking—do not add water.
• Cheddar — Grate it yourself from a block. Pre-shredded cheddar is coated in starch so it doesn’t stick to the packaging—that same starch prevents melting and gives an unpleasant grainy texture. A block of mature cheddar, 20 seconds on the grater, and you’re set.