Mmmm...light and dreamy...
Preheat oven to 350F. (180C)
Make the cheesecake base. Put graham crackers in food processor and grind till fine. Then add butter and cocoa. Mix again till it becomes damp and clumpy.
Pour everything into the spring form pan. Press the crumbs into the bottom of the pan. Make sure its compact and makes an even layer. Put the pan in the freezer while you make the filling.
Make filling. Melt chocolate chips in microwave, 10 seconds at a time. Remove and stir. If not completely melted, repeat for another 10 seconds.
In a mixer, beat cream cheese to soften it. Then add sugar and custard powder or cornstarch. Beat again to mix well.
Then add in the whole eggs, yolks and sour cream. Beat to mix well.
Add the cocoa and coffee mixture into the cheesecake batter. Add melted chocolate and mix everything till a smooth batter.
Take the spring form pan out of the freezer. Wrap the outside with aluminum foil. Make sure its wrapped well so that water will not get in.
Boil/microwave some water till hot.
Place wrapped spring form pan in a roasting pan and pour the cheesecake filling on top of the graham cracker layer. Then place roasting pan in oven.
Gently pour hot water into the roasting pan without letting water get into the cheesecake. Pour enough water till half of the pan is surrounded by water.
Bake for 45 mins to 1 hour till the top of the cheesecake set, but its ok if the underneath is wobbly.
Remove the foil and let the cake cool. Put cake in the fridge once its no longer hot. Let cake set in the fridge overnight. Only unspring the pan when ready to serve.
When ready to serve, make chocolate sauce. Melt chocolate chips and heavy cream in the microwave, 10 seconds at a time. Remove and stir. Only repeat another 10 seconds if chocolate is not melted. Drizzle the chocolate sauce on top of a cake using a spoon. Or you can put the chocolate sauce in a ziploc bag to create a pipping bag. Snip off the tip a little and drizzle on top of cake.