Onion and Spinach Tart

Ingredients

Pastry Case

• 250g plain flour

• 1 tsp salt

• 150g butter, cut into 1cm cubes

• 65ml chilled water

• 1 tsp vinegar

Onion & Spinach Filling

• 1 tbsp olive oil

• 30g unsalted butter

• 600g brown onions, thinly sliced

• 300g baby spinach

• 200g sour cream

• 100ml full cream milk

• 3 eggs

• ½ whole nutmeg, grated

• 50g vintage cheddar

Method

Make the pastry
1. Preheat the oven to 180°C.
2. Place the flour and salt in a large bowl. Rub in the butter with your fingertips until the mixture resembles coarse crumbs, then tip onto your workbench.
3. Sprinkle over the chilled water and vinegar. Using the palms of your hands, gently smear and press the dough together until it forms a cohesive mixture. Shape into a disc, wrap, and chill in the fridge for 30 minutes.
4. Roll out the pastry on a lightly floured surface and line a 24cm tart tin.
5. To blind bake, create a foil collar around the tart rim, then line the base with baking paper and fill with pastry weights. Bake for 20 minutes.
6. Remove the paper and weights but leave the foil collar in place. Continue baking for another 25 minutes, or until the pastry is golden brown. Remove the foil collar and set the case aside to cool.

Make the filling
7. In a large frying pan, warm the olive oil and melt the butter over medium heat. Add the onions and 2 tsp salt. Cook for about 1 hour, stirring often, until the onions are soft and golden (but not fully caramelised — they should remain juicy).
8. Meanwhile, blanch the spinach in a saucepan of boiling water. Drain in a colander, refresh under cold water, then squeeze out as much liquid as possible. Roughly chop and set aside.
9. In a jug, whisk together the sour cream, milk, and eggs. Add the grated nutmeg, plus a little salt and pepper, to season.
10. Spread the cooked onions and spinach evenly in the pastry case. Pour the custard mixture over the top.
11. Sprinkle with the cheddar and bake for about 40 minutes, or until the filling is set and golden on top.
12. Allow the tart to rest for 15 minutes before removing from the tin.