Preparation: cut the rhubarb into 2.5cm lengths. 1. Preheat the oven to 200C/400F/Gas 6. Place the butter, half of the sugar and the cinnamon in a pan and cook for 2 minutes. Arrange the rhubarb over the case of a 20cm greased and base lined cake tin, leaving a border around the edge. Pour over the cinnamon mixture. 2. Sift the flour into a bowl and rub in the fat. Stir in the ground almonds and remaining sugar and mix to a soft dough with the yolk and two tablespoons of cold water. 3. Roll out the dough to the same diameter as the tin and lay over the fruit. Bake for 30 minutes until the cake is golden. Leave in the tin for 5 minutes, then turn out. Serve warm with Fromage Frais.