250 millilitres lemon juice, or thereabouts (about 5 or 6 lemons)
Steps
Lemon Bars
Preheat oven to 160C/140C fan.
Cream the butter and sugar. Add the lemon zest. Add the flour. Shape into a dough and press into the lined tin. Prick all over then bake for 30 minutes. Take out and turn oven up to 180/160C fan.
Remove from the oven and let it cool fully in the tin. Once cold, carefully remove from the tin and dust with icing sugar before cutting into 16 squares.
Lemon Topping
Mix the sugar and flour in a bowl. Mix the eggs and lemon juice together, then sieve into a jug. Gradually add to the sugar mixture, mixing well to avoid lumps. Pour on top of the base and put into the hot oven for 20-25 minutes, until the top is just set.