- STEP 1
Heat the oven to 170C/335F/gas mark 3. Roll out the pastry and cut out a circle that is just slightly larger than the base of a 24cm spring-form cake tin. Place this inside the tin and refrigerate for 30 minutes. Cover with baking paper and baking beans, and bake blind for 15 minutes. Remove the beans and paper, and bake for another 10 minutes, or until the pastry is cooked through and golden. Remove from the oven and set aside to cool down.
- STEP 2
Meanwhile, heat the butter and oil in a large frying pan over low-medium heat, then sauté the onions and four of the garlic cloves, stirring from time to time, for 20 minutes or so, until the onions are soft and sweet but haven't taken on any colour. Set aside to cool.
- STEP 3
Whisk the eggs and yolks in a large mixing bowl, preferably with an electric mixer, until light and airy. Add the ricotta carefully and work just until it is well incorporated. Fold in the onion and garlic mix, basil, salt and pepper, then pour over the pastry and bake for 45-50 minutes, or until just set.
- STEP 4
While the tart is in the oven, blitz the sundried tomatoes, the picked leaves of three thyme sprigs, the reserved chopped garlic, a pinch of salt and a few tablespoons of the tomato oil – you want a smooth paste. Spread this mix evenly over the top of the tart as it comes out of the oven, top with three whole thyme sprigs, then return to the oven for five minutes. Remove, leave to cool, and serve warmish or cold.