Preheat oven to 180C fan/200C/400F.

Remove leaves from the cauliflower and trim the end to sit flat. Rub some of the oil on your hands and rub your hands over the cauliflower. Place in the preheated oven and roast for 30 minutes. remove from the oven and let cool. Keep the oven on.

Soak the porcini mushrooms in 70ml or so of just-boiled water for 10 minutes. Drain and press out the liquid; chop finely. You will be using about 50ml of the soaking water in the recipe so don't throw it out. Lots of flavour in it.

Heat the remaining olive oil in a large saute pan over a low-medium heat. Add the chopped onions and saute until soft. Add the garlic, chestnut mushrooms, porcini mushrooms, thyme and rosemary. Cook until the mushrooms lose their moisture and the pan gets almost dry. Now add the sherry (if using) and the saved porcini water, as well as the vegetable bouillon powder. Cook until the liquid absorbs. Take off the heat to cool to room temperature.

Mix the cream cheese/soft cheese and the miso into the mushroom mixture.  If you haven't used sherry you might want to add one teaspoon of lemon juice. In any case, taste the mixture and adjust to your liking. If you haven't used vegetable powder you may wish to add salt.

Take the puff pastry and roll it out to not more than 1/4 inch thick. You should have more pastry than you need. You can use the extra for making pastry cut out decorations. Place the cooled, cooked cauliflower in the centre and draw up the edges and pinch lightly to see that it will fully cover the cauliflower. If not, roll a bit more. Now let the pastry lay flat and cut a circle to fully accommodate the cauliflower. I also made four evenly-spaced v-notches, which helped to minimise pastry overlap when wrapping it up.

Place the cauliflower onto a plate or tray. Cover it with the mushroom mixture, squishing it between the florets, too. Drape the pastry over the cauliflower and draw the edges together, keeping one hand on it. If there is extra, trim this away with a sharp knife or scissors. Gently turn over the cauliflower (some mushrooms may fall off; just put them back on) and take care to seal the pastry around the cauliflower. Smooth the joins with damp fingers. You want to not have thicker bits of pastry as these will not cook well. Use some of the extra pastry to make shapes like stars, if you wish. 

Brush the pastry with the beaten egg and return to the refrigerator for half an hour to cool again.

Bake in the oven for 50 minutes to one hour. You may want to cover loosely with foil after 40 minutes to slow the browning of the pastry.

Remove the cauliflower from the oven to cool on the tray for 15 minutes. Transfer with a wide spatula, or cake lifter, to a plate and serve with a variety of vegetables and a jug of rich gravy.