Blitz the biscuits to a fine crumb in the food processor. Alternatively, pop the biscuits in a bag and bash with a rolling pin. Tip the biscuits into a bowl.
Add the melted butter and give it a quick mix.
Tip the crumb into a greased 23cm (9in) springform tin. Press down firmly to create an even base, then place in the fridge to chill.
Make cheesecake filling
Bloom the gelatine by placing it in a small bowl with 2 tbsp water. It should turn into a rubbery disc.
Put the cream in a heatproof bowl. Heat in the microwave in 30-second blasts until hot but not boiling.
Add the sugar, vanilla and gelatine. Whisk through gently until the gelatine is completely dissolved. Try not to whisk too enthusiastically as this will introduce air bubbles.
Add the cream cheese. Whisk gently until you have a smooth liquid mixture.
Divide the mixture evenly between 3 large bowls - you can use weighing scales to do this if you want to be accurate.
Leave one bowl uncoloured, colour one bowl blue and the other red.
Assemble the cheesecake
You will now work with each bowl, one by one, cleaning your utensils so that the colours don’t mix.
If one of your cheesecake mixtures sets in the bowl, just pop it in the microwave for a brief 10 seconds to loosen back up. Don’t allow it to boil.
Set the red and plain bowls aside and work first with the blue mixture.
Pour the blue filling into the tin and level off with a spatula.
Pop in the freezer (making sure it's sitting level!) for 15-30 minutes until definitely firm enough to add the next layer. If it's not, your new layer will sink into the previous one, causing them to be uneven - they may even bleed into each other. (See notes)
Now, making sure to use clean utensils, add the white layer before levelling off and returning it to the freezer for a further 15-30 minutes.
You can then repeat the process with the final red mixture, pouring into the tin and levelling off.
This time, place the tin in the fridge rather than the freezer and leave to chill overnight.
Serve
Run a warm knife around the inside edge, then unlock the springform tin. Transfer the cheesecake to a serving board.
Slice with a sharp knife to serve.
Notes
It's important that you don't freeze the cheesecake as this will upset the gelatine structure and prevent it from setting properly. If you don't want to use the freezer, or don't have room, you can use the fridge, just be aware it will take a bit longer to set.