Pithivier of potato, portobello mushroom and Gruyère, braised leeks and mushroom bisque

Instructions

1. Step 1

   Drop the button mushrooms into a very hot pan and cook until all the liquid has evaporated and they are dry

2. Step 2

   Once dry, add the butter and cook until the mushrooms are caramelised and golden brown

3. Step 3

   Drain off any excess butter and just barely cover the mushrooms with water. Bring to the boil

4. Step 4

   Remove the mushrooms from the heat and pour into a container. Seal with a lid and put in the fridge overnight to infuse

5. Step 5

   The next day, strain the liquid through a fine sieve and into a saucepan

6. Step 6

   Heat the liquid over a high heat until reduced, dark and syrupy

7. Step 7

   Add the cream, bring to a simmer and cook one minute more

8. Step 8

   Remove from the heat and adjust the seasoning to taste with salt and lemon juice

9. Step 9

   Bring a large pot of salted water to the boil

10. Step 10

    Cut out the potato slices into rings using the 6cm pastry ring. Add the potatoes and cook until tender

11. Step 11

    Meanwhile, melt 25g butter and add the spinach. Cook briefly, until just beginning to wilt, then tip into a colander to drain

12. Step 12

    Put the spinach into a clean tea towel and squeeze out all the water. Season the spinach heavily with salt and pepper, then put in the fridge to chill

13. Step 13

    Add the remaining 100g butter to a separate pan, and melt over a medium-high heat

14. Step 14

    Add the portobello mushrooms, skin side down, and cook on a medium heat until golden brown

15. Step 15

    Season with salt and flip the mushrooms. Add the chopped garlic and thyme leaves

16. Step 16

    Cook the mushrooms on the other side, basting with the garlicky butter, for 5 minutes more then season again and remove from the heat. Allow the mushrooms to rest for 10 minutes

17. Step 17

    Take the mushrooms out of the pan and pat them dry

18. Step 18

    Cut out 8 discs from the centre of the mushrooms using the 6cm pastry ring. Chill the cut mushrooms in the fridge

19. Step 19

    Place a 6cm pastry ring on a square of baking parchment. Put a mushroom into the bottom of the ring and then top it with a round of cheese

20. Step 20

    Press in a thin layer of dry spinach and then another disc of cheese. Add a potato disc, then more cheese, spinach again and more cheese

21. Step 21

    Finish with a mushroom disc (facing skin side up)

22. Step 22

    The final layers should be: mushroom, cheese, spinach, cheese, potato, cheese, spinach, cheese, mushroom. If the stack is too high you may need to trim the mushrooms horizontally. Press down tightly

23. Step 23

    Repeat this process 3 times to make 4 stacks, and then put them in the fridge (still in their pastry rings) to set

24. Step 24

    Place four of the 120mm pastry discs onto squares of baking parchment

25. Step 25

    Put one ring of filling on each pastry disc, then remove the ring

26. Step 26

    Brush egg yolk around the edge of the stack of filling

27. Step 27

    Place another 120mm pastry disc over the top of the filling and then smooth the pastry down the sides of the stacks, squeezing out the air as you go and closing it at the bottom

28. Step 28

    Crimp the base to seal the two pieces of pastry and brush egg yolk all over

29. Step 29

    Put the pithivier in the fridge to set the egg wash, about an hour. Repeat this egg washing process two more times, leaving the pastries to dry each time, so you have 3 layers of yolk

30. Step 30

    While the egg wash dries, make the leeks. Add the butter to a medium frying pan over a medium-high heat

31. Step 31

    Add the leeks, thyme and garlic to the pan

32. Step 32

    Cook the leeks, without stirring, until they are golden brown on one side. Season with salt

33. Step 33

    Turn the leeks over, and brown again on the other side. Taste and adjust the seasoning, then pull the pan off heat and leave the leeks to cool

34. Step 34

    Once you have finished egg washing the pastries, cut a small hole in the top of the pastry to release steam as it cooks, and cut off the excess pastry from the base leaving a small lip. You’ll need a cutter roughly 7cm in diameter

35. Step 35

    Preheat the oven to 180°C/gas mark 4

36. Step 36

    Score the domes of the pithiviers for decoration and put them on an oven tray

37. Step 37

    Bake for 20-25 minutes, or until golden brown

38. Step 38

    Warm through the leeks and the mushroom bisque. Divide the leeks between 4 serving bowls

39. Step 39

    Place a pithivier on each stack of leeks and pour around the warm mushroom bisque.