1. Preheat the oven to 190’c. Dissolve the stock in 350mls of water
2. start off, prepare the vegetables. Peel and slice the onion. Slice the mushrooms in half and finely slice the leek (you will need to wash the sliced leek to remove any dirt) Peel and slice the potatoes into chunks and place these in a large saucepan. Slice the carrots into discs.
3. Coarsely grate the cheddar cheese and set aside.
4. Heat a tablespoon of oil and cook until soft and translucent. Add the thyme leaves, garlic and leek, cook for another 5 minutes until the leeks begin to soften then add the mushrooms. Cook for another 3-5 minutes
5. Add a tablespoon of flour to the pan with the veg and stir so they are coated in the flour. Gradually add the stock, stirring after each addition then add half of the grated cheese. Keep stirring until you have a lovely cheese sauce (you may want to add more water if it seems too thick) Season to taste with salt and pepper. - This is the filling of your pie.
6. Pour the pie filling into an oven safe dish and scatter over the remaining cheese. Unroll the puff pastry and lay over the top of your pie filling (you may need to trim the pastry a little - but use these trimmings to decorate the pie!) prick the centre of the pastry with a fork or knife - this just gives somewhere for the steam to escape. Brush the surface of the pastry with a little milk. Bake in the oven for 30 - 35 minutes.
7. Whilst the pie is in the oven cook the carrots in a pan of simmering water until tender
8. Bring a large saucepan of water to a boil and carefully add the potato cubes. Cook for 10 - 15 minutes or until the potatoes are very soft. When the potatoes are done, drain and return to the pan. Add a little butter if you like and mash the potatoes until creamy with a potato masher.
9. Remove the pie from the oven and allow it to sit for a few minutes before serving with the carrots.
