Potato tart with leaks, mushrooms and mustard

Ingredients

For the potato pastry:

• 100g plain flour, plus extra for dusting
• salt and freshly ground black pepper

• 1 tsp English mustard powder
• 75g chilled unsalted butter, diced
• 100g mashed potato
• 1 tbsp iced water

Bake for 15 mins at 180ºC.

For the filling:

• 2 tbsp olive oil
• 400g leeks, trimmed and thinly sliced
• 100g chestnut mushrooms, sliced
• salt and freshly ground black pepper
• 75g mascarpone
• 1 tbsp Dijon mustard
• 50g Cornish blue, Stilton or Gorgonzola (or a similar vegetarian blue cheese), diced
• 1 crushed dried chillies (optional)

Bake for 45 mins at 180ºC.

Source bbc.com