For the dough, briefly knead butter in pieces with 150 g flour, 1 egg yolk, 40 g sugar and 2 tbsp. cold water to make a shortcrust pastry. Roll out rectangularly (approx. 15 x 25 cm) on a floured work surface.
Cut into 15 approx. 1 cm wide strips. Shorten 9 strips to a length of about 18 cm. Weave the 18 cm long and 25 cm long strips into a rectangular grid, starting at one corner. Cut the grid into 6 squares (each with an edge length of approx. 7 cm) and chill.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Roast pine nuts in a pan without fat until golden brown, let cool down. Wash apples. Cut off one lid each.
Slightly hollow out with a ball cutter while removing the core. Cut the apple lid into small pieces. Mix with the rest of the fruit pulp, sultanas, pine nuts, rum, 1 tbsp. sugar and lemon juice. Fill into the apples, pressing them lightly.
Place the dough grids on the apples. Carefully press on the edge. Break the cinnamon stick into 6 longish pieces. Put the apple stalk in the middle of the grid. Place the apples in an ovenproof dish. Bake in a hot oven for about 35 minutes.
Vanilla ice cream tastes good with it.