Rhubarb Cake - filling

Method

• Preheat the oven to 180C / 350°F Grease a 20cm / 8in cake pan, preferably loose-bottomed or springform. If you don't have one, use a regular cake pan but grease very well, line the bottom with a circle or parchment paper, and grease again.
• Trim the rhubarb and chop into pieces a couple of inches long. Put in a baking dish with the sugar and water and bake for 20-30 minutes, until the rhubarb is soft but still retains its shape. Drain the fruit and set aside you can reserve the juice to serve with the cake if you wish.
• Put the cornmeal, flour, baking powder, cinnamon and sugar in a large bowl, or in the bowl of a food processor or a stand mixer with the paddle attachment. Add the grated zest and the butter. If using your hands, rub the butter in as if making pastry - until the mixture resembles large crumbs. If using a food processor you just need to blitz for a few seconds, and if using a stand mixer, mix on low to medium speed for about 30 seconds.
• Break the egg into a small bowl and mix with the milk. Now add slowly to the crumble mix, stopping as soon as everything has come together to form a soft, sticky dough. You may not need all the liquid, or you may need a little more milk to get the right consistency.
• Press about two thirds of the crumble mixture into the bottom of the cake pan, pushing a couple of centimetres up the sides of the pan. Place the rhubarb on top, being careful to leave a small rim around the edges uncovered. Crumble the rest of the mixture over the fruit in fat lumps, using your fingers - don't worry if the fruit isn't all covered. Scatter over the brown sugar.
• Bake for 40-45 minutes. Cool the cake a little before removing from the pan.