This French cake derives its name from the fact that it can easily be prepared in advance and travels well, making it ideal for the weekend and perfect for picnics.
Preheat the oven to warm 170°C (325°F/Gas 3). Line a loaf tin (see Chef’s techniques), about 18 x 8 x 6.5 cm (7 x 3 x 2½ inches). Grease the paper and dust with flour.