Use a loose bottomed tin to make the dessert. This makes it so much easier to release the tart from the tin. You could even place a smaller circle of parchment on the base before pressing the biscuit mixture in, to facilitate release from the tin when removing it.
Baking the base makes it firmer and more stable, so it will not be as crumbly when cut into on serving. This is totally an optional step, the tart is just fine without baking too.
You can make the chocolate ganache filling in the microwave or on the hob, depending on your preference. Either way works just as well, so do what suits you best!
Tapping the tin gently on a work surface brings any air bubbles to the top. This means they can be popped and the layer smoothed over before leaving to set, giving you a nice clean finish to the top of the tart.
My suggestion for decoration is really just that! Feel free to decorate how you wish, with additional raspberries and drizzles of white chocolate, or just leave plain and enjoy as is!
Bring the tart out of the fridge for about 30 minutes before serving. This is to allow the chocolate layer to warm up and soften a little, for a truly luxurious dessert!