Filling: Place the milk, 30 grams of sugar, vanilla and lemon zest in a saucepan over low heat. 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 egg/sugar/flour mixture, whisking constantly. Return this mixture to the saucepan and stir constantly over medium low heat until the mixture thickens. This should take less than a minute. Turn off the heat, pour the filling into a bowl, cover with plastic wrap and refrigerate while you make and chill the pastry dough.
Pastry: In a bowl, whisk the eggs and sugar for 5 minutes until they lighten to a beige color. Then add the lemon zest, flour, and baking powder to your bowl. Next, gradually incorporate the butter (25g at a time) into the mixture with your hands until dough is smooth and soft. The butter will not be evenly combined, this is okay. If the dough is too soft, you may incorporate some of the additional 50 grams of flour at this time.
Shape dough into a disk, wrap in plastic wrap, and let it rest for 30 - 45 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). Put the larger circle in the tart pan, leaving a 2cm high border of pastry.
Prick the dough with a fork and pour all the custard filling inside, level well and cover with the other circle of pastry dough. Pinch to seal the edges of the pastry, prick the top with a fork, and decorate with almonds or pine nuts.
Bake: Place in the oven for 30-35 minutes. Afterf cooking, remove cake from the oven and cover with a clean cloth until cooled for serving. Sprinkle with powdered sugar just before serving. Enjoy!