1. Preheat the oven to 390˚F (200°C). Line a muffin tin with paper liners and set aside. Wash and dry the rhubarb, peel if necessary. Cut into small pieces. Add together with the raspberries (optional) and about 2 tablespoons of the sugar (or xylitol) to a bowl and mix – let marinate for some time.

 

2. Add the flour, brown sugar, rolled oats, cinnamon, and butter (in small pieces) for the streusel into a bowl and mix. Rub between your fingers until different sized streusel form. Place in the fridge until needed.

 

3. Add the egg for the batter and remaining sugar to a large bowl and mix until light and fluffy. Add the buttermilk, oil, and vanilla extract and mix in. Mix the flour with baking powder, and baking soda and add to the bowl – mix until just combined. Add the rhubarb mixture and fold in. Divide the batter between the prepared paper liners and sprinkle the streusel on top. Bake for 16-18 minutes or until a toothpick inserted into the center of the cupcakes comes out clean. Take the muffins out of the oven and remove from the muffin tin – transfer to a wire rack and let cool down completely. Dust with some confectioners’ sugar (optional) and/or serve with some rhubarb compote and vanilla sauce.