Crispy Potato and Beetroot Cake

I made this lovely potato cake for lunch this week and I have to say it is delicious. A really good way to use up those beetroot. It was a bit like a big potato rosti that had been baked. I served it with green salad.

Crispy Potato and Beetroot Cake with Sweet Mustard Sauce
(Serves 8)

25g butter, cubed, plus extra for greasing
2kg large Maris Piper potatoes, peeled and halved
1 onion
4 tbsp olive oil
500g beetroot, washed, trimmed and peeled
100g Jarlsberg cheese, rind removed
1 tbsp fresh lemon thyme leaves, plus extra to garnish

For the sweet mustard sauce
4 tbsp Dijon mustard
1 tbsp English mustard
2 tbsp white wine vinegar
1 tbsp caster sugar
3 tbsp extra virgin olive oil
2 tbsp roughly chopped fresh dill leaves

Preheat the oven to 190°C.  Grease a 23cm loose-bottom spring-form tin with butter, line the base with baking parchment and grease that too. Place a baking tray in the oven to heat up.

Put the potatoes into a large pan of water and bring to the boil. Cook for just 5 mins then drain and leave to cool completely.

Meanwhile, coarsely grate the onion and squeeze to remove any juice. Divide the onion evenly between 2 large mixing bowls. Coarsely grate the cooled potatoes into one bowl, tossing with the oil and some seasoning as you go. Coarsely grate the beetroot and Jarlsberg into the other bowl and toss with the thyme and some seasoning.

Scatter half of the potato mixture into the tin, without pressing it down, season, then scatter the beetroot mixture over the top, again without pressing down. Season again then finish with the remaining potato, without pressing it down, and dot with the butter.

Cover with a generous tent of foil that doesn't touch the top. Bake on the preheated tray for 1 hour, then remove the foil and cook for a further 30 mins or until tender and the top is crisp and golden.

Remove from the oven and leave to stand for 20 mins.

Meanwhile, whisk the sauce ingredients together with 2 tbsp warm water and season to taste.

 Loosen the edges of the cake with a knife, then remove the tin and parchment and slide onto a serving plate. Sprinkle with extra thyme leaves before cutting into wedges serve with the sauce alongside.