Wash and peel rhubarb and cut in pieces. Place in a pot along with raspberries, chia seeds, 1/2 tsp vanilla, xylitol or coconut blossom sugar. Bring to a boil and let simmer on low for about 8-10 minutes. Stir in between. Put aside.
Preheat oven to 350 °F/180°C and line a rectangular baking dish with baking paper.
In a mixing bowl mix oats, einkorn flour, coconut sugar reserving 1 tbsp, baking powder, salt and the other half tsp of vanilla. Add coconut oil and rub it in with your hands. Add oat milk and mix until you have a crumbly dough. You can use a kitchen machine for this as well.
Press a little more than half of the dough into the prepared baking pan. Spread the rhubarb-raspberry compote evenly on top and top with the remaining dough crumbs. Sprinkle with remaining tbsp of coconut blossom sugar.
Bake on the middle rack for 15-20 minutes. Let cool, slice and enjoy!