Preheat oven to 350 degrees. Line 30 cupcake tins with paper or foil cupcake liners. In double boiler, set over medium heat, melt the two third cup of chocolate chips, butter and vanilla. Stir until smooth. Remove from heat. Beat the eggs until frothy, using a whisk or electric mixer. Gradually, beat in the sugar until it dissolves. Gradually, beat in the flour. Fold in the chocolate mixture. Fill the cupcake tins one third full with the chocolate batter. Mash together the cream cheese, sugar and egg until blended. Fold in the half cup of chocolate chips. Drop a heaping teaspoonful of filling into each cupcake. Cover cream cheese filling with another generous spoonful of batter. Bake for 25 to 30 minutes. Let cupcakes cool completelyon a rack before storing in a covered container.