Crisp radicchio adds a little pepperiness to this creamy cheese and onion tart.
You will need a 23cm/9in loose-bottomed tart tin for this recipe.
For the pastry
- 225g/8oz plain flour, plus extra for dusting
- ½ tsp salt
- 50g/1¾oz cold butter, cubed
- 50g/1¾oz cold lard, cubed
For the filling
- 30g/1oz butter
- 1 red onion, finely sliced
- 1 tsp sugar
- 1 radicchio or red chicory head, finely sliced
- 3 medium free-range eggs
- 250ml/9fl oz double cream
- 1 thyme sprig, leaves only
- 1 tsp dijon mustard
- 75g/2½oz gruyere or Cornish vintage Gouda
- salt and freshly ground black pepper
- green salad leaves (optional)
To make the pastry, sift the flour and salt into a food processor or large mixing bowl. Add the cubed cold butter and lard and work it together quickly until the mixture resembles coarse breadcrumbs.
Stir in 1½–2 tbsp cold water, a little at a time, until the dough begins to come together. Turn the mixture out onto a lightly floured surface and knead briefly into a smooth ball. Roll the dough into a disc about 8cm/3¼in wider than your 23cm/9in loose-bottomed tart tin
Using a floured rolling pin, lift the pastry off the worktop and drape it in the tin. Gently press the pastry into the fluted sides of the tin using your fingers and trim off any excess. Cover with clingfilm and chill in the fridge for 30 minutes.
Preheat the oven to 200C/180C Fan/Gas 6. Remove the pastry case from the fridge, line with parchment paper and tip in baking beans or rice, making sure they’re spread evenly across the base. Bake for 15 minutes, removing the paper and baking beans for the final 4–5 minutes to crisp up the pastry. Once cooked, remove the pastry from the oven and allow to cool.
To make the filling, melt the butter in a large frying pan, add the onion and sugar and cook over a medium-low heat for 5 minutes or until the onion has softened. Add the sliced radicchio and cook for a further 5 minutes until soft and wilted.
Whisk the eggs and cream in a bowl, stir in the thyme and season with salt and pepper.
Smooth the mustard over the base of the cooled pastry case and arrange the onion and radicchio on top in an even layer. Scatter the cheese on top and pour over the cream mixture.
Reduce the oven temperature to 160C/140C Fan/Gas 3. Bake for 25 minutes until the cream mixture is set.
Remove from the oven and allow to cool in the tin for 15 minutes. Cut into slices and serve with a green salad.