Torta della Nonna

Method

1. Pastry (pasta frolla): in a bowl mix the flour, baking powder, sugar and salt, and finely grate in half of the lemon zest (the rest goes into the custard). Add the cold butter in 1 cm cubes and quickly rub it in with your fingertips until it looks like damp sand. Add the beaten egg (for half an egg, beat a whole one and use half; for the largest size add the yolk too), stir with a spatula, then gather it with your hands just until it comes together. Over-kneading melts the butter and makes the pastry tough. Flatten into a disc, wrap and chill for 1 h.

   Add in this stepPlain flour 135 gBaking powder ½ tspCaster sugar for the pastry 55 gSalt 1 pinchUnwaxed lemon ¼Cold unsalted butter 70 gEgg for the pastry 1

2. Custard: separate the eggs and keep one white aside for brushing. Put the milk in a pan with 2–3 strips of lemon peel cut with a vegetable peeler and warm over medium heat for 4 min, until small bubbles appear at the edge, then turn off the heat. Meanwhile whisk the yolks, sugar and cornflour in a bowl until pale. Pour in the hot milk a little at a time, whisking constantly, fish out the peel and pour everything back into the pan. Cook over medium-low heat for 3 min, whisking non-stop and scraping the bottom, until it bubbles once or twice and is thick enough to hold the whisk marks. Take off the heat and stir in the vanilla.

   Add in this stepWhole milk 220 mlUnwaxed lemon ¼Eggs (yolks for the custard, white for brushing) 2Caster sugar for the custard 55 gCornflour 18 gVanilla extract ½ tsp

   medium heat→medium-low heat

3. Scrape the custard into a wide dish, press cling film onto the surface so no skin forms, and let it cool for 30 min. It should be lukewarm or cool, or it will melt the pastry.

4. Preheat the oven to 180 °C for 15 min. Line the base of a 16 cm tart tin with a removable bottom with baking paper. Roll two thirds of the pastry between lightly floured sheets of baking paper to 3–4 mm, line the tin, press it neatly up the sides and prick the base with a fork. Whisk the cooled custard briefly until smooth, spoon it in and level it. Roll the rest of the pastry to the size of the tin, lay it on top as a lid, press the edges to seal and trim off the excess. Cut a small hole in the centre to let steam escape.

   oven

5. Lightly beat the reserved egg white, brush a thin layer over the lid, scatter the pine nuts evenly and press them in gently with your palm. Bake on the lower shelf of the oven for 30 min, until the top is evenly golden and the edges are light brown. If the pine nuts colour too fast, lay a loose sheet of foil on top.

   Add in this stepPine nuts 25 g

   oven

6. Leave the tart in its tin on a wire rack for at least 1 h until completely cool before unmoulding; warm custard runs and won't slice. Just before serving, sift over the icing sugar and cut into slices.

   Add in this stepIcing sugar 2 tsp