Mix biscuit crumbs, sugar, butter and cocoa. Press onto bottom and up the sides of a 22cm springform pan. Set crust aside.
Beat cream cheese until smooth. Gradually add sweetened condensed milk and beat well. Add vanilla and eggs then beat on medium speed until smooth.
Toss 1/3 of the miniature chocolate chips with the 1 teaspoon flour to coat (this keeps them from sinking to the bottom of the cake). Mix into cheese mixture.
Pour chocolate chip / cream cheese mixture into prepared crust. Sprinkle top with remaining chocolate chips.
Bake at 150 degrees C for 1 hour. Turn off oven (do not open oven door) and leave the cake in the oven to cool for another hour. Remove from oven and cool completely. Refrigerate before removing sides of pan. Keep cake refrigerated until time to serve.