1. Start with marinating the rhubarb. Wash and dry the rhubarb and cut into small dices. Add together with the smashed raspberries to a bowl and mix with 2 tbsp. of the sugar – cover and let sit for about 1 hour.

2. While the rhubarb is marinating prepare the streusel. Line a 9×9 inches (22x22cm) square baking tin with some baking parchment and set aside. Add flour, sugar, and salt to a large bowl and mix to combine. Add the butter in small pieces as well as the vanilla extract and mix everything with your hands until you get different sized streusel – make sure there is no more flour on the bottom of the bowl. Take a little bit more than half of the streusel and transfer it to the prepared baking tin. Press to the bottom and into the corners to get one even layer, prick several times with a fork. Place with the remaining streusel in the fridge until the rhubarb is ready – at least 20 minutes.

3. Preheat the oven to 375°F (190°C). Bake the crust for about 15 minutes until it gets some color around the edges. Take out of the oven and lower the temperature to 350°F (180°C). Let cool down for a bit.

4. Drain the rhubarb if there is a lot of liquid – some is ok though. Add the lemon juice and sugar and mix to combine. Sprinkle the flour on top and mix until all is well combined. Pour that filling on top of the baked crust and spread evenly. Sprinkle with the streusel from the fridge and bake for 40-50 minutes or until the streusel have a nice golden color and the filling is bubbly. Take out of the oven and let cool down completely before removing it from the tin.

5. If you want to add the glaze on top (optional), mix the confectioners’ sugar with 1 tsp. of the milk and the vanilla extract and add more milk until the consistency is nice and thick and not too runny. Drizzle over the rhubarb bars and let harden/dry before slicing.