Blitz your shortbread biscuits to a fine crumb. Melt your unsalted butter carefully, and then add into your biscuits.
Blitz the biscuits again to combine, and add to the bottom of your 8"/20cm deep springform tin.
For the Cheesecake Mix!
Add your cream cheese to a stand mixer bowl, or a large bowl. Add in your icing sugar, and whisk until smooth using the whisk attachment on the stand mixer, or using the whisks on your electric hand whisk.
Pour in your double cream, and whisk. As the mixture is starting to thicken, add in your lemon juice (and yellow food colouring if using), and whisk again.
Continue to whisk until very thick. Be careful to check the mixture frequently to see how thick it is, and fold through with a spatula to make it all even.
Once whisked, spread over the biscuit base, and then leave to set in the fridge fully for at least 5-6 hours, or preferably over night for longer.
For the Decoration!
Whisk together your double cream and icing sugar until pipeable. Pipe onto your cheesecake with your favourite tip.
Add a bit of lemon per slice, and sprinkle over some lemon zest.