Grease a casserole dish (20 cm Ø, approx. 1.1 l capacity) well. Caramelise 100 g sugar until golden yellow. Add 1 tablespoon butter and jam, simmer for about 1 minute. Spread the caramel on the bottom of the baking dish, let it cool down.
Wash plums, halve, stone and cut into slices. Peel, quarter, core and slice the apple. Spread the fruit on the caramel.
Preheat oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer). Coarsely chop the almonds, roast them in a pan without fat and take them out. Whip cream until stiff. Cream 100 g butter, 100 g sugar and 1 pinch of salt. Stir in eggs one by one. Mix flour, baking powder and lemon zest and stir in briefly. Fold in almonds and cream.
Put the dough into the mould and smooth it down. Bake in a hot oven for 45-50 minutes. Cover if necessary after about 30 minutes. Take the tart out of the oven, turn it over immediately and let it cool down.