First wash the rhubarb, peel and cut into 1-2 cm pieces. Mix with the 2 tablespoons of sugar in a bowl and let steep for about 1 hour. Then put in a sieve and drain well.
For the crumble, put the ingredients in a bowl and work them into a crumbly dough with your hands or the kneading stick of the mixer.
Grease a springform pan (26 cm diameter) and add about half of the crumble. Press firmly with your hands on the floor and then prebake in the oven at 180 degrees for about 10 minutes.
For the batter, stir the butter with the sugar until frothy. Gradually stir in the eggs well one by one. Mix the flour, nuts and baking powder together and then fold in.
Carefully coat the pre-baked crumble base with warmed strawberry jam. Pour the batter on top and smooth it out.
Then cover evenly with the rhubarb and sprinkle with the remaining crumble.
Bake in the oven at 180 degrees for about 45 minutes.
Dust them with a little icing sugar when they have cooled down.