For the crumble, put 60 g butter, 60 g sugar and 120 g flour in a bowl and work with a dough hook until a uniformly mixed dough has formed. If the butter is very cold, it should be cut into flakes beforehand. Cover the crumble dough and place in a cool place.
Peel and quarter the apples and remove the casing. Halve or third the apple quarters lengthways - depending on the size - and cut into approx. 1 cm thick slices. Put in a bowl and mix with a little lemon juice. Cut the onion into very fine cubes and also add to the bowl. Add the ginger and cinnamon and mix.
Heat 60 g butter in an uncoated pan or saucepan and fry the apple and onion mixture over full heat. After approx. 4 minutes add 60 g sugar and fold in for 1 minute. Now deglaze with rum and cook, stirring constantly, until the liquid has thickened a little. Then place in a baking pan and sprinkle with crumble.
Bake in a preheated oven (top / bottom heat) at 180 ° C for 25 minutes.
Tastes best while it is still warm and then particularly good with vanilla ice cream and bacon strips.