In the thermomix, add the sugar, and thin slices of peeled lemon skin and mix sp5/20 secs. (I have a fantastic zester so it's easier for me to just add the zest to the sugar than to try to peel the lemon first)
Add the butterfly then add the butter and mix 1 min/speed 4 until pale and creamy - you may need to scrape down the sides half way through.
Keep the blades running at speed 4, and add the eggs, then add the flour through the lid of the Thermomix bowl while it's running - about 1 minute to add it all.
Oil or line a baking tray and spoon the mixture in and level it out.
Bake for 45-50 mins until a thin skewer inserted into the centre of the cake comes out clean.
Mix together the juice of the lemon and 85g icing sugar. Pierce holes around the cake using a fork or knife edge) then pour the drizzle over the warm cake. Make sure to cover all the cake.
The juice will sink in and the sugar will form a lovely, crisp topping. Sieve over additional icing sugar if you wish for the white colouring. Top with more grated lemon.
Leave in the tin until completely cool, then remove and serve.
Recipe by Keeper of the Kitchen at https://www.keeperofthekitchen.com/2014/09/14/lemon-drizzle-cake-recipe/