Lemon bars on shortbread crust

Soften butter at room temperature for about 20 minutes. Heat the conventional oven to 180 °C. Line a square 20 cm tin with paper. Mix 120 g flour, 0.25 tsp salt and 28 g icing sugar, then work in butter until crumbly. Press very firmly into the base and edges so filling cannot seep underneath.

Separate eggs and weigh 14 g of yolk in a small bowl, without using the whites. In another bowl crack whole eggs, beat and weigh 200 g without shell. Mix the weighed eggs and yolk with white sugar and 21 g icing sugar without foaming. Add the remaining 30 g flour and 0.125 tsp salt, then 152 g lemon juice. Mix until smooth.

Bake the base for about 35 minutes at 180 °C until golden. During baking, rest the filling for at least 15 minutes so bubbles disappear. Remove the base and lower the oven to 165 °C. Gently pour filling onto the still-hot base and bake for about 30 minutes until set and relatively dry on top, with no liquid centre.

Cool completely on a rack for about 120 minutes. Lift out with paper and cut into about 16 small squares. Sift over the remaining 10 g icing sugar just before serving.