Grandmother's crumble tart with lemon pastry cream and pine nuts

A fairly quick, impressive cake, with crisp pastry and soft cream to rival classic torta della nonna. Use organic lemons if possible; mine came from my Gargnano garden on Lake Garda, where lemons are abundant.
INGREDIENTS
PASTRY
400 g '00' flour
100 g butter
150 sugar
Half a sachet baking powder (8 g)
2 eggs
40 g pine nuts
LEMON PASTRY CREAM
4 lemons, zest
500 ml whole milk
6 egg yolks
150 g sugar
3O g cornflour
30 g '00' flour
I prepare the cream. I heat milk with yellow zest of 3 lemons, without boiling, in microwave or a pan. I put yolks and sugar in a saucepan. I whisk until pale. I add sifted flour and starch. I mix without lumps. I add strained milk. I heat, stirring continuously. I turn off once thickened. I put in a cold dish and mix in grated lemon zest. I cover with cling film touching the surface and refrigerate to cool. PASTRY I put all ingredients in a processor or bowl. I mix until crumbly. I line a tin with parchment, press in half the pastry and leave a side rim. I spread cooled cream over it. I scatter some remaining crumbs and pine nuts. I finish with remaining crumbs and press lightly with my palm. I bake at 180°C for 30 minutes, remove and cool, then dust with icing sugar.
Try it: delicious!