Combine the celeriac, potato, onion, chilli flakes and chopped sage in a bowl and season well with salt and pepper. Crack in the egg and scatter over the cornflour, then use a fork to thoroughly mix everything together, so that the egg is well distributed throughout the mixture.

Put the bacon under a hot grill to crisp up. Meanwhile, heat the butter in a non-stick frying pan over a medium-high heat until it bubbles then starts to brown and smell nutty. Add the extra sage leaves and swirl them around in the butter to infuse, then remove with a slotted spoon and place on kitchen paper for later.

Spoon enough of the celeriac mixture to form teacup-sized patties (about 7cm) into the pan, pressing them down gently with the back of a spoon or spatula. Turn the heat down a little and fry the hash browns for 3-5 mins on each side until golden and crunchy. Place in a warm oven with the grilled bacon while you fry some eggs, if you like. Serve the hash browns with the fried eggs on top, if using, along with the bacon and crispy sage.