Grease and line a 12" x 9" tin, pre-heat your oven to 160C Fan/180C/350F/Gas Mark
Use a food processor to crush the digestive biscuits into crumbs. Then mix in the zest of half of one of the lemons
Melt the butter, mix it into the biscuit crumbs, and press the mixture into a greased and lined baking tray
Bake it for 10 minutes, then leave it to cool completely
Whisk the ricotta cheese, cream cheese and caster sugar together
Add the limoncello, vanilla extract, the zest of 1 ½ of the lemons, and the eggs (add one egg at a time) and mix in well
Pour the cheesecake mixture into the baking tray over the cooked crust. Bake it for 30 minutes
Once fully cool, remove from the tin and cut into squares, decorate with half a slice of lemon. Store them in the fridge to keep them fresh