Fit the Knife Blade to the Food Processor bowl.

Preheat the oven to 180°C.

Add celeriac and water into the saucepan.

Heat over a medium heat.

Boil until soft.

Remove the celeriac with a slotted spoon, leaving the water in the pan, and place in a large bowl.

Add farro into the pan of hot water.

Simmer for 20 minutes until tender.

Drain and leave to cool.

Roughly mash the celeriac and add to the farro.

Add oil into the sauté pan.

Heat over a medium heat.

Add the onion and garlic into the pan.

Cook over a medium heat until soft.

Add mushrooms into the pan.

Increase the heat and allow the mushrooms to reduce in volume and start to colour.

Remove from the heat and add the cooked vegetables to the celeriac.

Add nuts and herbs into the Food Processor.

Blend until everything is roughly chopped.

Transfer the contents to the celeriac.

Add the flour and butter into the Food Processor.

Pulse until the butter is distributed through the flour.

With the machine still running add the egg yolks and water.

Mix until the pastry comes together.

Transfer the pastry to a work surface and bring together.

Wrap in plastic wrap.

Chill for 30 minutes.

Line a work surface with parchment paper and lightly flour.

Place the pastry on the paper and roll into a large rectangle about 30 cm x 45 cm.

Pile the filling down the middle of the pastry leaving a 10 cm border along each long edge and a 5 cm on along the short edge.

Using a sharp knife make cuts at a 45° angle from the mixture to the edge of the pastry, around 1.5 cm apart.

Starting from the top fold one strip over the filling.

Fold the top strip on the other side over the filling.

Fold the rest of the strips over the filling, alternating sides.

Tuck the ends underneath.

Brush with beaten egg.

Lift the parchment paper onto a baking tray.

Bake for 45 minutes at 180°C.

Serve