Line a 8 inch square baking dish with parchment paper. Make sure to have extra paper on the sides to make it easier to remove the cake later.
Blitz the graham cracker to fine crumbs or alternatively smash with rolling pin
Melt the butter and mix it with the powdered cracker. Pat this down into the baking dish press and even out with a glass ramekin.
Bake 375° F for 8-9 minutes. Allow it to come room temperature.
For the cheese filling :
Either use a hand blender or stand mixer with paddle attachment beat the cream cheese until smooth on slow for a minute then add the ricotta cheese beat until it is combined.
Add the sugar, lemon juice and finally towards the end zest give it a good stir.Pour the mixture on to the prepared base.
Take a large baking dish pour 1 1/2 cup of hot water(I use hot tap water) and gently keep the cheese cake dish into it.This is called bain marie.Bake this for 50 -55 minutes. The center will be jiggly and the edges would be firm sometimes even slighly brown.
Once done remove the cake dish from the water cover loosely with lid so the center doesnot sink in. Allow this to come to room temp. Wipe off all the water vaper fallen on the cake then cover and refrigerate for atleast 4-6 hours or best overnight.
To make the lemon pie topping :
Mix all the ingredients (under topping ) adding 1 cup of cold tap water. (Note :Corn starch will not mix evenly in warm or hot water it will simply clump up)
Heat a pan on the lowest heat pour the mixture into it and continiously stir it without taking your hand off.
Allow the mixture to thicken and become creamy now add butter as soon as it melts switch off the heat and transfer to another container. Allow this to cool down.
Decorate the cake :
Lift the parchment paper out of the dish, cut the cheese cake into squares.
Spoon a little lemon pie topping on each square. Keep a lemon slice, sugar flower and mint leaves.
While cutting the bars it can crumble so take a large cutting knife dip it in boiling hot water, wipe it dry and cut repeat for every cut for neat edges. The heat prevents the fat from sticking to the knife.