Sift the flour, baking powder and salt. Put the butter in a mixing bowl and beat until soft and smooth.
Place the egg yolks and sugar in a separate bowl and whisk until light in colour. Add the eggs to the soften butter and beat until fully combined.
Then fold in the sifted dry ingredients. Mix together the ingredients to form a dough. Wrap in cling film and leave to chill in the fridge for a couple of hours or freeze for up to 1 month.
Take the pastry from the fridge and roll the pastry out between two sheets of greaseproof paper. This is necessary because the pastry can be quite sticky, roll it out to a thickness of about 8mm.
Place the rolled out dough on a baking tray, remove the top layer of greaseproof paper and return to the fridge for an hour.
Preheat the oven to 180C Fan and bake the pate sable for 20-25 minutes until it turns golden. As soon as the pastry is done, remove it from the oven and using a round pastry cutter that is 7.5cm diameter, cut out 10 circles. It's best to do this when the pastry is warm. Don't remove the circles of pastry, leave them to cool before moving them.
To make the creme patissiere, add the milk and vanilla pod to a saucepan and bring to the boil. Turn off the heat and leave the milk to infuse while you mix the egg yolks, sugar and flour. Whisk until the mixture is a light coloured thick liquid.
Strain the infused milk onto the egg mixture and whisk until combined. Return the mixture to the saucepan and whisk until thickened.
Remove the creme patissiere and place it in the bowl of a stand mixer with the flat beater attached. Beat the creme patissiere until it cools to room temperature. On a medium speed slowly add the cubes of butter, beating until they are full incorporated.
This takes a few minutes and it looks as though the butter and creme patissiere are never going to combine, however after a few minutes, the mixture changes to resemble a light buttercream and comes together.
To assemble the tarts, take the sable breton and spoon a teaspoon of strawberry jam in the centre of the pastry. Pipe or spread a small amount of the creme mousseline on top of the jam and cover it completely. Don't be tempted to add too much creme as it will splurge out when you add the fruit.
Decorate with chopped and sliced fruit of your choice, I used strawberries, raspberries and Japanese wineberries.
Finally heat up the apricot jam with a tablespoon of water and then using a pastry brush, glaze the fruit with the jam to get the real patisserie shop look. Store these in the fridge and eat within 3 days.