This serves at least 6 adults.
Turn on the oven at 200 degrees C.
Slice the rhubarbs and put in a buttered oven dish.
Add the raspberries.
By mistake I deleted the photo where I added the potato flour. On top of the berries add it and mix it with the rhubarbs & raspberries to avoid the berries getting too juicy.
Then add the sugar evenly, followed by..
..and the oatmeal. It is important to do it in that order.
Grate the white chocolate on top of the oatmeal. You could very well use a grater that gives you bigger pieces of chocolate but this is what I had. As you can see I kept some of the larger pieces.
Finally shave the butter on top of the pie. using a cheese cutter. Cover the pie and then bake in the oven for about 20 minutes. Watch it regularly so the white chocolate doesn't burn.
Serve with whipped cream. You can of course choose icecream or vanilla sauce but the chocolate makes it rather sweet.