For the crema/custard:

1. Heat the milk and the lemon peel in a saucepan on low/medium heat until the scalding point, that is just before it starts to boil. Remove the lemon peel.
2. In a bowl, beat the egg yolks and the sugar until light and smooth but not frothy.
3. Sift the cornstarch on top of the egg mixture, and whisk to combine.
4. Add one ladle of the warm milk to the egg mixture and mix gently to temper. Then, add the rest of the milk and mix well.
5. Pour the mixture back on the stove on low/medium heat, and stir continuously with a wooden spoon or a whisk until you see it is thickening.
6. When the crema/custard has reached a nice consistency, that is not too runny and not too set, remove from heat.
7. If you see any lumps, pass it through a strainer, if not, place immediately in a wide bowl, cover with plastic wrap, making sure it touches the cream and seals it from air. Store it in the refrigerator until ready to use.

For the pastry:

1. In the bowl of a food processor or stand mixer, add the flour, baking powder, and shaved cold butter. Pulse or mix until a crumbly texture is achieved.
2. Then, add the sugar, the vanilla extract or paste, and egg. Pulse or mix until it starts to come together but still looks crumbly. Do not overwork.
3. Take the crumbs out of the bowl, shape into a ball, flatten it, then wrap in plastic and set in the fridge for at least 30 minutes.
4. Preheat the oven to 180° C/350° F. Set one rack on the middle.
5. Take the dough out of the fridge, lightly flour a work surface, and with a rolling pin roll it out to a thickness of 3-4 mm, adding flour underneath the dough and on the rolling pin if it gets sticky.
6. Using a 5inch/13cm round cutter, cut as many circles on the dough as you can. Gather and re-roll all the scraps of dough. You should end up with 5 rounds of dough. 
7. Grease 5 x 4 inch/10 cm tartlet pans then gently place the rounds of dough in each one. I used a spatula to lift the dough into the tartlet pans.
8. Press them gently at the bottom and on the sides, then cut any excess dough from the top. Prick the bottom of each pastry. Repeat for all the tartlet pans.
9. Then, place pieces of parchment paper, more or less the size of the base, in each tartlet pans and add pie weights, or dried beans. This is called blind baking.
10. Bake in the pre-heated oven for 15-20 minutes, or until they are a nice golden colour on the sides.
11. Once out of the oven, remove the weight/beans and the parchment paper and let cool completely on a rack.

Assembly:

1. With a spoon, or a piping bag with a round tip, fill each pastry shells with the crema. Add the raspberries starting from the outer circle, pressing lightly into the cream.
2. Optional, sprinkle with icing sugar or, if you want them shiny, you can brush the raspberries with gelatin or simply, thin some apricot jam and lightly brush the top.