For the dough, first knead 250 g flour, egg, 2 tbsp. oil and 100 ml lukewarm water to a smooth dough, then knead vigorously for about 10 minutes on the work surface. Shape into a ball, brush thinly with oil and wrap in foil.
Allow to rest for approx. 30 minutes at room temperature.
For the filling, crumble the bread finely. Peel apples, remove seeds and cut into small pieces. Mix the apple pieces with lemon juice, rum, raisins, sugar, gingerbread spice, bread and 1 tbsp. flour.
Roll out the dough on a floured tea towel. Then pull out with floured hands to form a larger rectangle (approx. 45 x 60 cm).
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Line a baking tray with baking paper. Melt butter. Spread the dough with about half of the butter. Spread the apple mixture approx. 10 cm wide with a little distance between them on one narrow side of the dough, leaving approx. 5 cm free on both long sides.
Tap the edges of the long sides inwards over the filling. Roll up the dough from the apple side using the cloth. Place the dough on the tray with the seam side down. Spread with the rest of the butter.
Bake in a hot oven for 30-35 minutes. Take out, let cool and dust with icing sugar. Tastes warm and cold.