Method:

1. Preheat oven to 170C.
2. Melt the butter in a medium heavy-bottomed saucepan, stirring constantly. Mix the flour into the melted butter with a whisk until it turns into a foamy paste, approximately 2 minutes, but be sure not to brown it.
3. Slowly pour in the milk, whisking continuously and stir until the sauce thickens. Bring it to a light simmer, lower the heat before adding the cheese. Stir it though until melted and season to taste with sea salt and cracked pepper. Remove from the heat.
4. Grease a deep baking dish and place a layer of celeriac over the base, followed by a layer of scattered onions and then a layer of potato. Spread over some of the bechamel sauce and spread evenly over the potato. Repeat this layering process until all the ingredients have been used, finishing with a layer of bechamel. Combine the panko crumbs and parsley together and sprinkle evenly over the top of the potato followed by a drizzle of extra virgin olive oil. Bake in the oven for 30-40 minutes. Increase the heat for the final 5-10 minutes if you would like more golden colour on the top.
5. Serve alongside any grilled or roasted meat dish or leafy salad.

Our friends at Wine Selectors suggest pairing this dish with a Gamay.