Wash all the bowls, mug and small spoons before preparing raspberry tartlets recipe.
Take out flour in a cup and tip it with your hand. Now put small amount of butter and sugar in it and whisk again.
Beat the mixture until it gets slight solid and add the egg yolk and few drops of water as well. Soon it will resemble a fine breadcrumb.
Take the slight hard breadcrumb mixture and prepare a pastry into a ball shape. Cover the ball shape mixture cling film and put into a refrigerator to chill for an hour.
Wait for pastry to chill in the refrigerator while start preparing tartlet. Take a cup of milk and put into a saucepan. Start heating milk but be aware that milk gets not boiled rather heat the milk in an over a gentle heat.
Now empty the egg bowl and pour the yolks into a large mixing bowl and vigorously whisk the whole mixture. Put the sugar in the mixture and whisk again until the mixture turns pale and doubles in volume.
Put the mixture in the saucepan and cook over a medium heat. While cooking, stir the mixture continuously, until the mixture starts to boil and thicken. Leave the mixture in the pan from the heat. Leave the whole mixture to cool in the saucepan before putting to the fridge to chill thoroughly.
Preheat the oven to 220C/gas 7 and remove pastry starting off the fridge. Take out the chilled pastry and put into oven to bake. When the pastry is fully baked, fill it with the top with the raspberries.
Serve the raspberries tartlets with a dust of icing sugar and serve.