1. Place biscuits in a plastic bag, and crush them into very fine pieces.
2. Mix melted butter, cinnamon powder and sugar into crushed biscuits, and stir until well combined. Press firmly onto base of 7 inch cake pan. Place in refridgerator and reserve for later use.
3. Preheat oven to 150C. Beat cream cheese with beater, then add in sugar and continue beating. Slowly beat in egg, flour, lemon zest and yoghurt, and continue beating until mixture is smooth and fine.
4. Pour cake mixture into baking pan, and place in 150C oven to bake for about 50 minutes. Take out and let cool. Place in fridge until it is thouroughly cooled and serve.