There are many variations on how to make this.
A casserole dish is buttered. Into this is placed a layer of fried diced potatoes. Some recipes have you boil them then slice them first; other recipes have you peel them but put the potatoes in raw. Most advise that waxy potatoes are best.
Then a layer of onions and smoked bacon (lardons) mixed with crème fraîche and some melted Reblochon cheese, then it is topped with large slices of Reblochon cheese, and bacon pieces. You invert the cheese so that it goes on top rind side up. The rind of the cheese will turn into a crispy crust.
It is baked, and served hot.
A few versions line the dish with pie crust, pâte brisé, or flaky pastry first. Some advise flaky pastry. A few swap in double-cream for the crème fraîche.
Dates from the 1980s. Was launched by marketers to promote the sale of Reblochon cheese.
Severson, Kim. Finding the Perfect Tartiflette in France. New York: New York Times. Travel Section. 29 April 2007.
Waitrose Magazine. Trade Secrets: Tartiflette.