Preheat oven to 180C/350F (standard) or 160 C/320 F (fan/convection). Grease a 9 inch springform pan.
Break the digestive biscuits into half and put them into a food processor. Pulse till crumbs are formed, and then add the softened butter. Pulse again till combined. The mixture will look like wet sand.
Grease the bottom of the springform pan with butter or oil. Press the crushed biscuits onto bottom and edges of springform pan. Use the back of a spoon or the side of a glass to press the biscuit in. Bake the biscuit crust for 5 minutes, and then let it cool.
Place cream cheese and sugar in a large mixing bowl. Use an electric whisk or stand mixer to mix both together till smooth and creamy. Add milk, and then add the eggs one at a time, whisking just enough to incorporate. The mixture should be creamy and lump free at this point.
Add the sour cream, vanilla essence, flour and lemon zest. Fold through with a rubber spatula. Don’t over mix as it can result in air bubbles.
At this point, cover the bottom of the spring form tin with aluminium foil. Put two layers of aluminium foil around the bottom springform pan in order to ensure there is no leakage.
Pour the cheesecake filling into the cooled springform tin.
Place the spring form tin in a roasting / baking tray. The roasting tray / baking tray should be able to fit the spring form tin.
At this point you need to add hot water from the side till it reaches halfway up the sides.
My methodology is to put the roasting tray in the oven, and then add the hot water in the tray from the sides using a kettle or saucepan. I find that the safest method as I don’t have to carry a tray with hot water from the counter to the oven.
Bake the cheesecake for about 45 minutes – 50 minutes till it is ready. The top will be very light golden brown, and almost fact. It should also jiggle slightly when gently shake the pan.
Once the cheesecake is ready, turn off the oven and let the cake cool in the oven for about 1 – 1.5 hours.
Take out the cheesecake from the oven, and let it cool till room temperature after which you can put it to chill in the fridge for 4 – 6 hours or overnight.
Serve chilled with berries or a sauce on the side.