Heat the oil in a stew pot over a medium heat. Cook the onions for five minutes until softened. Stir in the sage and flour until the onions are well coated.
Gradually stir in the chicken stock and mustard until incorporated.
Remove from the heat and stir in the leftover turkey, potatoes, vegetables and crème fraiche until combined.
Top with the leftover stuffing and spread to an even layer.
Cover with the lid and bake for 40minutes until heated through.
6-8 people
15 minutes