• Heat the oven to 170°C (150°C fan). Grease a deep, loose-bottomed or springform 18 cm cake tin and line the base of it with baking parchment.
• Beat the butter and caster sugar together with an electric whisk until pale and fluffy, about 4 minutes. Add eggs, one at the time, beating well after each addition, then stir in the lemon zest and vanilla. Fold in the 250g of flour, ½ teaspoon baking powder, ½ teaspoon of salt and 100g Greek yogurt. Mix until the ingredients are JUST combined.
• Spoon the mixture into the prepared tin and smooth the top with a spatula. Bake in the centre of the oven for 50-55 minutes, until golden brown on top and firm to the touch. Cool the cake in the tin for 10 minutes, then remove from the tin and cool on a wire rack completely. 

For the icing:

• Sieve 400g of icing sugar into a bowl and beat in enough of the lemon juice to create a thick icing. Set the cake on a cake stand or a plate and spoon over the icing, allowing it to drip down the sides a little.

For the candied lemon peel:

• Peel large, wide strips from 2 large lemons using a vegetable peeler. Remove any white pith with a sharp knife, then julienne the peel into very thin matchsticks. In a small saucepan, add the granulated sugar and water and set it over a medium heat until the sugar has dissolved. Add the lemon peel and simmer gently for 15 minutes then scoop the peel with slotted spoon and set on a paper towel to cool. Use to decorate the cake with it.