Peel and finely chop the onion. Pluck basil leaves from the stems and cut into strips. Mash sheep's cheese with a fork, stir in crème fraiche. Add onion and basil.
Season with salt and pepper. Halve baguette lengthwise and cut into rhombs. Bake in a preheated oven (electric cooker: 200 °C/ gas: level 3) until golden brown. Spread a small lettuce leaf and a little sheep's cheese cream on each