Tartiflette is a French speciality of the Savoy region. Rich and indulgent, it's a favourite apres ski dinner. Traditionally it's made with Reblochon cheese, potatoes, lardons and a generous smothering of cream. Reblochon cheese is not always easy to get hold of so I have adapted the recipe to use cheddar and gruyere. In order to make it a more rounded dish, I've also included chicken and spinach.