1. First make the jam. Sterilize a jam jar by washing in warm soapy water and placing on a baking tray in an oven at 140'C for about 10 minutes, till dried out inside. Put the washed raspberries and sugar into the large saucepan and put on a low heat. Stir with a wooden spoon until the berries and sugar turn into a runny liquid mixture. Add the butter, turn up the heat to high and cook for 8 to 10 minutes, stirring all the time so it doesn't stick. To know if the jam is ready use a teaspoon to take out a bit of mixture and place on a small plate with an ice cube on it. If it settles on the plate and looks like jam, it's ready. Pour the jam into the sterilized jar and leave to cool while you make the biscuits.
2. Preheat the oven to 170'C and butter the baking tray. To make the biscuits, sieve the flour, icing sugar and pinch of salt into a big mixing bowl. Then add the slightly softened butter and use your fingers to rub the butter into the flour mix.
3. When the mixture looks like coarse breadcrumbs, add in the two egg yolks and mix them into the flour mixture to form a dough. (This is a messy job so don't worry if it sticks to your hands!) When you have a ball of dough, place it on a lightly floured surface and roll to about 1/2 cm thick.
4. When you have rolled it out to the right thickness, it's time to choose your cutter. I used a teapot cutter for this recipe and you need two halves to each sandwich so you need 12 biscuits in total. Lay out your cut biscuits carefully on a buttered tray as the dough is delicate and put in the oven for 10 - 12 minutes until they are light golden brown and slightly spread.
5. Take the biscuits off the tray and leave to cool on the wire rack. When they are completely cold, put a dollop of jam on the front of one biscuit and sandwich together with the back of another. Repeat with the remaining biscuits and sprinkle with icing sugar before serving with a nice cup of tea.