1. What's the best type of cake for this? Because the bottom one will have to support to the top one.

Butter cake or mud cake

2. What do I use as support for the top one? I'm thinking a disc the same size as the top cake, with pillars going through the bottom cake, is that right?

The top one should be fine to sit on the bottom one but you can use skewers to secure it if you're going to be moving it or taking it in the car.

3. What icing would be best to get it a decent white colour? My buttercream is always still kinda yellow, no matter how much I beat it. I'm totally utterly useless as fondant so that's no good, plus I need to stick the shards to it.

You can google ways to get perfectly white butter cream or you can buy a pre mix from a cake decorating ship or spotlight.

4. How do I colour white chocolate? I can't use liquid colours, can I? And do I melt it with anything else to make it better, or just the chocolate and colour?

Use powdered colour to dye chocolate, also available from cake decorating shops.


5. What's the best way to colour the toffee? I've never actually made toffee before so this is going to be completely new to me.

Put food dye in the water before you start cooking