Sift the flour, sugar and salt into a bowl. Rub in the butter until it look like breadcrumbs, and stir in the lime zest. Press this mixture into a greased tin 23cm x 33cm (9 x 13 inch) and bake at 170 °C/325°F/gas mark 3 for 20 minutes.

Whisk the eggs, sugar, lemon juice and rind until well combined. Pour over the warm base and return to the oven for 40 minutes until set. Cool before cutting into bars and dust with icing sugar.

Per serving: 2322 Calories (kcal); 221g Total Fat; (83% calories from fat); 27g Protein; 69g Carbohydrate; 1361mg Cholesterol; 309mg Sodium Food Exchanges: 0 Grain(Starch); 3 Lean Meat; 0 Vegetable; 1/2 Fruit; 42 1/2 Fat; 3 1/2 Other Carbohydrates