Parmentier was the man who popularised potatoes in France in the 18th century. Whenever you see his name on a dish, it will contain potatoes," Roux says. "This dish is a special version of cottage or shepherd's pie and very delicious."
There's something about a warm, meaty filling covered in potatoes that's just perfect for autumn and winter. As for the duck, "In France, you can buy confit duck legs in most butchers' shops," Roux says, "but if you have trouble finding them in the UK, look for vacuum-packed or canned." Or, alternatively, you can buy duck legs and confit them yourself – you can find simple recipes online.