Preheat your oven to 200C/180C fan/gas 6.

Roll out the puff pastry onto a baking tray.

Using a knife, mark out a border around the edge of the puff pastry.

Spoon the mustard on the bottom of the puff pastry dough.

Then sprinkle with a thick layer of cheese.

Place the sliced tomatoes on top of the mustard and cheese layers.

Season with salt, pepper and herbs de Provence (or substitute with rosemary, thyme).

Bake in the oven for about 20 minutes, or until nicely browned.

Remove from oven and let rest for around 15 minutes.