Filling: Place the milk in a saucepan over low heat, add 30 grams of the sugar, vanilla and lemon zest. Separately, in a bowl mix the egg yolks and the remaining 30 grams of sugar with the flour and stir well until the mixture is smooth.
Once the milk is just below a simmer, gradually add the milk to the eggs mixture, whisking constantly. Return this mixture to the saucepan and stir constantly over medium low heat until the mixture thickens. Turn off the heat and pour the cream into a bowl and cover with plastic wrap and refrigerate.
Pastry: In a bowl whisk the eggs and sugar for 5 minutes until light yellow, then add the lemon zest, the flour, and the baking powder. Working by hand, gradually add the butter until dough is smooth and soft. If the dough is too soft, you may incorporate some of the additional 50 grams of flour at this time.
Shape into a disk, wrap in plastic wrap, and let it rest for 30 minutes in the refrigerator. Preheat oven to 350 degrees F. Divide the pastry into two parts (one slightly larger), then roll the pastry into two circles (one slightly wider than the tart pan because it must contain the cream inside) put the larger circle in the tart pan, leaving a 2 cm high border of pastry.
Prick the dough with a fork and pour all the cream inside, level well and cover with the other circle of pastry. Seal the edges of the pastry, prick the top with a fork, and decorate with the almonds or pine nuts.
Bake: Place in the oven for 30-35 minutes. At the end of cooking remove the cake from the oven and cover with a clean cloth until serving. Sprinkle with powdered sugar just before serving. Enjoy!