Portobello Mushroom Wellington

Ingredients:
8 large portobello mushrooms
2 garlic cloves, diced
1 teaspoon thyme leaves
2 tablespoons extra virgin olive oil
100g (3 ½ ounces) spinach
1/8 teaspoon nutmeg, grated
1 tablespoon Marsala
3 egg yolks, beaten
320g (about 11 oz.) ready-rolled puff pastry sheet
1 teaspoon black onion seeds
100g (1/2 cup) butter
2 tablespoons extra virgin olive oil
4 white onions, sliced
1 teaspoon thyme leaves
2 garlic cloves, sliced
1 tablespoon Marsala
3 eggs
100g (about ¾ cup) all-purpose flour
300ml (1 ¼ cups) whole milk
1 teaspoon chopped rosemary
Sunflower oil, for frying
2 tablespoons olive oil
2 shallots, diced
2 garlic cloves, diced
1 teaspoon chopped thyme leaves
50ml (about 1/4 cup) dry sherry (Manzanilla or Fino)
200ml (about 3/4 cup) vegetable stock
250ml (1 cup) heavy cream
Steamed broccolini and kale

Instructions:
Wipe the mushrooms with a piece of damp paper towel to remove dirt and grit; twist out and discard the stalks. Place in a large roasting tray with the garlic, thyme, Marsala, oil and salt and pepper. Rub each mushroom with the garlicky oil and cover the tray with tin foil. Place in an oven heated to 180°C (350°F) for 15 minutes, until the mushrooms have reduced in size and are soft throughout. Remove the foil, drain away the cooking liquid and set the tray on a cool surface while you prepare the rest of the Wellington.
For the onions, melt the butter with the oil in a medium frying pan over a medium heat. When all the butter has melted, add the onions with a pinch of salt and cook, stirring regularly, until the onions turn soft and translucent. Add the thyme, garlic and Marsala to the pan and continue to cook for a further 15 minutes, stirring every 2 minutes until the onions are golden and caramelized all over. Remove the onions from the pan to a plate lined with paper towels to drain away the excess oil and butter. Leave to cool completely.
Next, make the pancakes. Whisk the eggs with the flour in a large mixing bowl, then slowly pour in the milk, whisking all the time until no lumps are visible. Add the chopped rosemary and season with salt and pepper. Cover with plastic wrap and set aside for 10 minutes until bubbles appear on the surface of the batter.
Warm a 26 cm. (10 in.) non-stick frying pan with a splash of sunflower oil over a medium-high heat. Pour half a ladle of the pancake batter into the pan and swirl to evenly coat the base.
Cook each pancake for a minute on each side, until lightly golden, then flip and cook the other side. The mixture should produce 6-8 thin pancakes.
Cook the spinach for a minute with a pinch of salt and a grating of nutmeg in a frying pan until bright green and just wilted. Squeeze out as much moisture as you can through a sieve, then dry on kitchen paper.
Lay out a 30cm (12 in.) piece of plastic wrap on a clean work surface, then lay 4 cooled pancakes alongside each other on the plastic wrap (you can use any extra when making the Wellington), ensuring a generous amount of overlap so that there is a continuous length down the middle of the plastic wrap. Brush the pancake all over with some of the egg yolk, then arrange the spinach down the middle of the pancakes, leaving a couple of centimeters at each end without spinach.
Place the mushrooms on top of the spinach, placing one on top of the other, giving four layers of two down the center. Top the mushrooms with the caramelized onion mixture, then use the plastic wrap to lift the pancake over the filling on either side. Fold over the ends and continue rolling until you have a tight cylinder shape. If there are any gaps, use the extra pancakes to patch up, brushing with egg yolk as you go. Wrap the pancake tightly with plastic wrap and chill in the fridge for 20 minutes.
Roll out the sheet of puff pastry and brush with egg yolk. Remove the chilled pancake cylinder from the fridge and unwrap the cling film. Place in the middle of the puff pastry sheet and fold the pastry over the filled pancake to encase it completely. Crimp the sides of the pastry and brush with egg yolk all over. Scatter over the black onion seeds and cook in an oven heated to 180°C (350°F) for 25-30 minutes, until dark golden all over.
While the Wellington is cooking, make the sauce. Heat the olive oil in a small saucepan over a medium heat, then add the shallots and garlic with a pinch of salt and cook for 5 minutes, until soft and translucent. Add the thyme and dry sherry and bring to the boil. Reduce for 3 minutes, then add the stock. Continue to cook until the liquid has reduced by half, then add the heavy cream and turn the heat to low. Cook for 5 minutes, then season with salt and pepper.
Serve the Wellington with the tarragon cream sauce in a jug for pouring over and steamed broccolini and kale on the side.