Preheat the oven to Gas Mark 3, 170ºC, fan 150ºC. Wash the tomatoes and put them whole into a roasting tin. Drizzle with the olive oil and season well. Roast for 20 minutes, then rest until they reach room temperature. Meanwhile, roughly chop half the basil leaves (save the rest to decorate the tart) and mix with the goat's cheese. Smooth this over the base of a cooked shortcrust pastry case. Neatly place the tomatoes in one layer on top of the goat's cheese so there are no gaps. Drizzle with the balsamic glaze and decorate with torn basil leaves. Serve with some salad leaves, if you like. See more Picnic recipes.