Make sure to measure the fruit and nuts precisely, no extra, because if you use a small 19 x 9-cm (7.5 x 3.5-inch) pan, the amount of batter comes right up the edge of the pan. You can easily find these disposable aluminum pans in grocery stores.
Wrap the cake in aluminum foil and freeze. With a sharp knife, slice the frozen cake as thinly as possible. Dry the slices, side by side, on a baking sheet lined with parchment paper in the middle of the oven for about 18 minutes at 170 °C (325 °F). Be careful not to overbrown the crackers. Let them cool on the baking sheet.