Parsnip with Old Winchester, hazelnut and onion brioche

This is a very complex recipe, so be sure to read it through and confirm you're up to the challenge! There are a few elements which need making the day before (the parsnip mousse, hazelnut insert and first step of the brioche), but you can also prepare other elements in advance to make things easier

To make the hazelnut insert, preheat an oven to 160°C/gas mark 2. Place the hazelnuts in a roasting tray and season with the sea salt and the hazelnut oil, making sure all the nuts are evenly coated. Roast in the oven and cook until a deep golden brown – this should take around 20-30 minutes. Transfer the roasted nuts into a blender and blitz until a praline is formed. Place the praline onto a tray lined with baking paper, roll it flat then place in the freezer to set and firm up

To make the parsnip purée, heat the rapeseed oil in a heavy bottomed pan, then add the parsnips and salt. Keep the heat at a medium level and slowly caramelise the parsnip until a golden brown, continually moving the parsnips to get an even colour. Once golden all over add the butter and allow it to foam to coat the parsnips nicely and finish off cooking. Transfer to a blender and blitz until smooth

Weigh out 230g of the purée whilst still warm, then take roughly 50g and stir in the bloomed gelatine until dissolved. Stir this back into the rest of the purée. Whip the cream to soft peaks, then fold into the purée in 3 stages to create a mousse. Transfer to a piping bag

Pipe the mousse into your chosen moulds until half full. Carefully cut out a disc of the frozen hazelnut praline the same diameter as the moulds, then place one of these on top of each mousse. Fill the rest of the mould with more mousse. Place the moulds into the freezer and reserve

To make the brioche, mix the flour, yeast, salt, eggs and milk in a food mixer with the dough hook attached and mix for 5 minutes on speed 3. Add in a third of the soft butter, mix again for 3 minutes, then repeat with the next two-thirds of butter until completely incorporated. Place the dough into a bowl, cover with cling film and rest overnight in the fridge

To make the onion consommé, place a large, heavy-bottomed pan over a medium heat with a splash of vegetable oil, the onions, garlic, thyme and a good pinch of salt. Clingfilm the pan tightly and place over a very low heat. You want the onions to steam in their natural juices and after that start to slowly and naturally caramelise. This will take a couple of hours

While the onions cook you can make the Old Winchester cream. Place the cream in a pan and bring to the boil. Stir in the grated cheese and stir until completely melted. Whisk in the bloomed gelatin, stir to dissolve, then pass through a sieve into a container. Leave to set for 4 hours

Once the onions have caramelised, add the madeira, turn up the heat and reduce to a syrup. Add the water and bring up to the simmer then cook for 10–15 minutes, skimming off any impurities which form on the surface of the liquid. Transfer to a pressure cooker and cook for 90 minutes. Pass through a muslin cloth and season, then pass through a coffee filter and reserve. You now have a super clear and flavourful onion consommé

To make the onion gel, take 200ml of the onion consommé and whisk the ultratex into it to thicken. Transfer to a squeezy bottle and reserve

To make the onion glaze for the mousses, place 310ml of the remaining onion consommé into a pan. Mix the sugar and pectin together then whisk into the liquid and bring to the boil, continuously whisking for two minutes. Remove from the heat then add the bloomed gelatine and blitz with a stick blender until smooth. Leave to cool to 30ºC then blitz again with the stick blender

Take the frozen parsnip mousses out of the freezer and very gently unmould them. Stick a small cocktail stick into the bottom of each mousse and dip them into the onion glaze until half coated. Gently place them on a tray lined with baking paper (with the glazed side facing up) and store in the fridge to defrost – this will take at least 2 hours

To make the parsnip crisps, use a peeler to slice thin ribbons of parsnip, stopping when you reach the core. Weigh the parsnip strips, then work out 1% of that weight and toss with that amount of sea salt. Leave for 10 minutes, then pat the strips dry to remove excess water. Deep-fry at 170ºC in vegetable oil until golden brown and crisp. Leave to cool and store in an airtight container

After 4 hours, whip the Old Winchester cream using a whisk and place back into a clean container, wide enough to create rochers from. Cover and reserve in the fridge

To finish the brioche, weigh out 450g of the dough and roll it until 8mm thick, roughly 40cm long and 15cm wide. Spread over the caramelised onions and generously sprinkle over the old Winchester. Roll this up into a log and leave to rest for 20 minutes in the fridge. After this time, cut the log into 3cm pieces, turn them on their sides and place into a muffin tray. Allow to prove at room temperature for 2 hours

To cook the baby parsnips, place them in a vacuum bag with the rest of the ingredients. Seal and steam at 86ºC for 12 minutes or until tender. Empty the bag into a pan and colour up a little before serving. If you don't have sous-vide equipment, you can simply steam the parsnips, then colour up in a pan with the butter, thyme and a drizzle of hazelnut oil. Keep warm

When ready to serve, preheat the oven to 160ºC/gas mark 3. Remove the parsnip mousses from the fridge so they can come to room temperature. Brush the brioche with egg wash and bake for 10–12 minutes until perfectly golden. Brush with melted butter and sprinkle with thyme leaves before serving

To plate, garnish the mousse with shards of parsnip crisps and picked thyme leaves. Place this onto the plate with the onion gel piped around it and a couple of small rochers of the Old Winchester cream. Add the roasted hazelnuts and nasturtium leaves and serve the warm brioche on the side. Enjoy and give yourself a pat on the back!