Pre-heat the oven to 185C
Mix the egg (or equivalent) and sugar.
Then add all the other ingredients and mix to form a dough like mixture. Add the rhubarb last and mix through lightly, leaving chunks.
Line a baking tray and take tablespoon sized amounts and make cookie shapes on the baking paper.
Bake for 15 minutes.
If using fresh rhubarb (which is preferable) bake it in the oven at a low heat for 20 mins or steam it for 10 mins and then lightly mash.