- Combine flour, salt, yeast, and water in a large bowl. (To account for rising, the bowl should be at least 4 to 6 times the volume of the dough.) Mix with hands or a wooden spoon until no dry flour remains.
- Cover bowl tightly with clingfilm and leave to rise for 24 hours in the fridge. Take the dough out at least 2 hours before cooking time to let it become more malleable.
- Oil a 20cm x 30cm metal oven tray. Tip the dough onto a flat oiled oven tray (this'll make it easier to move around later). Stretch it out to roughly 20x 60cm, place the Boursin on top of one half and fold over the other side, pressing together the sides to seal in the Boursin. Carefully transfer it to the oiled oven dish for baking.
- Cover the dish with clingfilm and let it rise for another two hours, preheating the oven to 200°C after the first hour. Remove the clingfilm - the top should have bubbled up nicely.
- Time to decorate! Use your creativity here, but we find it's good to start with the stems of the flowers to give you an idea of your layout. Use blobs of Boursin to represent the centre of the flowers surrounded by yellow pepper petals, tomatoes as flowers and the halved black olives to represent pebbles on the ground. Make sure you cover tender basil leaves with oil to stop them drying out!
- When you've created your masterpiece pop it in the oven and bake it until the focaccia has risen and is cooked to your liking. Keep an eye on the toppings so they don't burn.
- If you want your base to be super crisp at this point you can place the tray over a low hob and fry it for a few minutes.
- Serve fresh and warm.