Winter vegetable pie

Ingredients: 
For the filling:
½ small squash
½ swede
2 carrots
¼ large celeriac
2 leeks
50g emmental, grated
50g butter
50g flour
600ml milk
1 onion
1tbsp Dijon mustard
50g parmesan, grated
1/2tbsp finely chopped fresh thyme and parsley
1/4tsp freshly grated nutmeg
For the pastry:
25g parmesan, grated
100g flour
1tbsp olive oil
1tbsp butter
Method: 

• Make the pastry by sifting the flour into a bowl with a pinch of salt and rubbing in the oil and butter
• Grate the Parmesan and add
• Add 1-2tbsp of warm water and stir in with a metal knife, and then bring the pastry together with your hands
• Chill the pastry for 30 minutes 
• Meanwhile cut the squash, celeriac, carrots and swede into 1 inch or 2.5cm chunks
• Cut the leeks length ways and cut into 2” chunks
• Steam the vegetables for 10-15 minutes until tender
• Preheat the oven to 220C
• Make the sauce by melting the butter and adding the onion, cooking very gently for 15 minutes
• Stir in the flour with a wooden spoon, and then add the milk a little at a time
• Season the sauce with nutmeg, salt and pepper and simmer for 5 minutes, then add the mustard, cheese and herbs
• Grease a 22cm pie dish
• Mix the vegetables with the sauce and place in the bottom of the dish, then sprinkle with the cheese
• Roil out the pastry and cover the vegetables
• Cut the middle of the pie with a knife to let out the steam and cook for 25 minutes until golden

Original Source: 
Izzy Silvester