Mix the soft fat, 300 g sugar, flour, baking powder and eggs into crumbles using the dough hooks of the hand mixer. Spread 2/3 of the quantity on a deep baking tray coated with fat and press it down. Crumble the remaining dough and chopped almonds with your hands and chill. Clean, wash and cut the rhubarb into small pieces (should make 750 g.) Mix with 100 g sugar and spread on the base. Distribute chilled crumbles as well. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 35-40 minutes. Serve dusted with icing sugar