Put the plant-based burger patties in a large mixing bowl

Season with salt and pepper and mash with a fork until they all break down and come together

Use your hands to shape them into one thick sausage shape that will make up the 'fillet' in the wellington

Wrap the sausage in clingfilm, place on a baking tray and put into the fridge to firm up while you make the mushroom duxelles

Clean and halve the chestnut mushrooms, then add them to a food processor with the cooked chestnuts, garlic clove and a pinch each of salt and pepper and blend to a paste

Heat the drizzle of oil in a large frying pan over a high heat

Once warm, add the mushroom paste, pick the leaves from the thyme sprigs and add them too

Mix well and cook for 5-10 minutes, stirring every now and then, until the paste has dried out

Once cooked, leave to one side to cool

Wipe out the pan youmade the duxelles in and heat a drizzle of olive oil in the pan over a high heat

Remove the cling film from the fillet and add it to the pan

Sear on each side until evenly browned all over

Transfer to a plate and brush all over with Dijon mustard, then set aside

Lay a large piece of cling film on your work surface and spread the mushroom mixture on top to the width of the fillet

Lay the fillet at the edge of the mushroom layer

Tightly roll the fillet into a sausage shape

Twist the ends of the cling film so it holds tightly together, then refrigerate for 15 minutes to firm up

Unroll one sheet of puff pastry onto a large baking sheet, keeping the paper on the bottom

Unwrap the fillet from the cling film and place it on the middle of the pastry sheet

Brush almond milk a thumbs width around the edge of the fillet

Place another pastry sheet over the top of the fillet and press down around the base where the almond milk has been brushed to seal the two pastry sheets together

Cut around the edge of the pastry, a thumbs-width from the fillet, to make a neat border, keeping any leftover pastry to decorate

Wrap the wellington tightly in cling film and chill for another 10 minutes, or overnight if you're super organised

Preheat oven to 190°C

Remove the cling film and decorate the pastry with the off-cuts if you like, re-rolling and cutting them as necessary-we like to cover the wellington in pastry strips placed diagonally across the top

Make a hole in the pastry with a chopstick to prevent the pastry from splitting

Glaze the wellington all over with almond milk and sprinkle with sesame seeds

Cook the wellington in the oven for 45-50 minutes, until golden and delicious

Rest for 15 minutes to allow the juices to settle, then transfer to a cutting board and slice