Lemon yoghurt Polenta Cake
Preheat the oven to 180°C, 350°F, Gas 4. Line the base of a 23cm (9in) spring form tin and brush a little sunflower oil around the inside. Crack the eggs into a bowl along with the natural yoghurt, the sunflower oil and the lemon zest and the lemon juice. Whisk together to mix well, then stir in the plain flour, the caster sugar, the fine polenta, the baking powder and the pinch of salt.
Tip the mixture into the prepared tin and bake it for 35-40 minutes until a skewer inserted in to the centre comes out clean. Remove the cake from the oven and allow it to sit in the tin for 20 minutes before taking it out of the tin to finish cooling.
To make the icing, whisk the mascarpone, the lemon juice and the icing sugar in a bowl and set it aside until the cake is cool. When you're ready to ice the cake, use a long-bladed knife to split the cake in half. Place the bottom half on a plate or a cake stand - I find it handy to slide the base of the spring form tin under the cake half to transport it. Spread out enough of the icing to cover the bottom half (as if you were generously buttering a piece of bread) then place the other half of the cake on top. Use the remainder of the icing to ice the top of the cake.