Grease the fat pan (approx. 32 x 39 cm; approx. 3.5 cm deep). Clean, wash and cut rhubarb into finger-thick pieces. Carve peaches crosswise. Scald with boiling water, rinse cold and peel off the skin. Cut peaches in half, stone them and cut them into slices
Melt butter at low heat. Mix flour, baking powder, sugar and 1 pinch of salt. Add eggs. Knead in the liquid fat little by little with a hand mixer. Then briefly knead into crumbles with your hands. Press 2/3 of the crumbles in the fat pan as a base
Stir the jam until smooth. Spread about 3/4 of the jam on the pastry base. Spread rhubarb and peaches on top. Sprinkle the rest of the crumbles on top and spread the rest of the jam in patches. Bake in the preheated oven (electric oven: 200 °C/circulating air: 175 °C/gas: level 3) on the lowest rack (gas: see oven manufacturer) for approx. 35 minutes. Let them cool down