|3 tbsp olive oil
|2 large onions, halved and finely sliced
|2 cloves garlic, crushed
|2 tbsp Dijon mustard
|100g gruyère, grated
|50g Grana Padano, grated
|300g cherry tomatoes, halved (use a variety of colours, if you like)
|350g Rogers Foods All Purpose Flour
|150ml olive oil
|To make the pastry, mix the flour with 1 tsp salt then stir in the olive oil and just enough water so it comes together as a dough (you’ll need about 4-5 tbsp). Roll out the pastry between 2 sheets of baking paper to the thickness of a 20p coin then use to line a 23cm or 24cm tart tine. Trim the edge and chill while you make the filling.
|Heat 3 tbsp olive oil in a large non-stick frying pan and add the onions and a good pinch of salt. Fry very gently for 20-30 minutes or until meltingly soft and golden. Add the garlic and cook for another couple of minutes. Cool and mix in the mustard and cheeses.
|Heat the oven to 190C/fan 170C/gas 5. Bake the tart shell for 20 minutes then take out and cool.
|Spread the cheesy onions over the base of the tart. Sit the tomatoes on top in a single layer, cut-side up, and season. Put the tart back in the oven for another 20-25 minutes or until the pastry is crisp and the tomatoes are slightly golden. Serve just-warm.