While the dough is refrigerating, start peeling the rhubarb and cut it into rather thin slices.
Peel the apple as well and cut it into little cubes. Put the fruits into a bowl and scatter them with the 100g of sugar. Let them macerate for 30 minutes.
Drain the rhubarb-apple mixture and cook it over a low heat for 10 minutes.
In a middle-sized bowl mix the butter, the remaining sugar and the ground almonds. Add the eggs and mix until you get an even dough.
Now you can take the dough out of the fridge and roll it out. Shape it depending on your base. As you can see I used a rectangular one but a round one works perfectly fine as well.
Transfer it to your tart base and prick it all over with a fork.
Scatter the base with the remaining ground almonds.
Garnish the base with the cooked rhubarb and cover the fruits with the almond crumble.
Bake for 30 minutes and let it cool down for another 30 minutes as well.
Enjoy!!!