In a mixing bowl, add the flour and sugar and stir. Divide the butter into chunks and rub into the flour until it looks like breadcrumbs. Add the yolks and vanilla and bring together with your hands to form a smooth dough. On a piece of cling film, make a disc out of the dough, wrap and refrigerate for 30mins
Roll out the pastry and lay into a greased 9inch tart tin. Prick the base all over with a fork and trim the over-hanging edges. Chill in the fridge for around an hour to help with the shrinkage when it's in the oven. You can use the extra dough to cut shapes to bake&decorate.
Preheat the oven to 180c/160c fan. Line the pastry with greaseproof paper and baking beans/rice. Bake for 15mins, remove the paper and beans and bake for a further 10 mins. If you have pastry shapes, bake for 10-15 mins until nicely browned.
Leave the tart case in the tin and cool on a wire rack.
In a microwaveable bowl, add 210g of the chocolate, 70ml of the cream and 30g of butter. Microwave for 1 minute, then at 10 second intervals, stirring in between. When it starts to melt add the purple food gel. Stir gently to combine until glossy.
Add this to the pastry case and push in raspberries to fill the bottom of the tart with gaps in between.
Leave this to set in the fridge for about 10 minutes.
Repeat this step but with the pink food gel, then again leaving the last layer the original colour.
Chill in the fridge.
Add the cream, icing sugar and vanilla to a bowl and whisk until soft peaks form, being careful not to overwhisk. Add the cream to a piping bag.
Dust the tart with a little icing sugar, then pipe the cream onto your tart as you wish to decorate. Arrange your other toppings as you wish.