Heat the oven to 200C/180C/gas 6. Put the rhubarb in a baking dish (ours was a 30cm rectangular dish). Sprinkle over the orange zest and juice and vanilla paste. Add 2 tbsp of water and mix until the rhubarb is coated.

Put the oats, soy milk, baking powder, peanut butter, egg and banana into a large bowl. Mix until combined.

Pour over the rhubarb and smooth out the top. Bake for 35-40 mins until set. Leave to stand for a few minutes, then serve with Greek yogurt and a drizzle of honey, if you like.