To make salted caramel, heat sugar in a non-stick pan and let it caramelize. Add cream and butter, mix and cook till the butter melts. Add sea salt and mix well. Remove from heat and set aside.
Preheat oven to 180º C.
Take the crushed biscuits in a bowl. Reserve 1 tablespoon salted caramel, add remaining and mix well. Spread the mixture in a 5 inch loose bottom baking tin evenly to make the crust. Set aside.
Separate egg yolks from whites and put into two different bowls.
Cream together cream cheese, hung yogurt and castor sugar in a third bowl till smooth.
Lightly beat egg yolks, add to the cheese-sugar mixture and mix well.
Add lemon juice and vanilla essence and mix well. Add reserved salted caramel and coffee powder and mix well.
Beat egg whites with a hand blender till soft peaks are formed. Fold this into the cream cheese mixture.
Pour the mixture over the crust lined in the baking tin and spread. Place it in the preheated oven and bake for 30 minutes. Remove from oven and cool.
Cut into wedges, drizzle caramel sauce on top, garnish with mint sprig and serve.