Preheat the oven to 180 C (350 F). Grease and flour a 12 cup bundt cake pan.
In a large bowl, stir together cake mix, pudding mix, sour cream, vegetable oil, eggs and water until well combined.
Stir in the chocolate chips, then transfer batter to prepared pan.
Bake for 50-55 minutes until cake top is springy to touch, and toothpick comes out clean (or mostly clean, the chocolate chips might show melted chocolate on the toothpick)
Cool in pan for at least one hour, then invert onto serving plate and top with the chocolate glaze or sprinkle some icing sugar on top.
For the chocolate glaze:
In a double boiler (a heatproof bowl set over a pan of simmering water), melt together the chocolate, butter, and corn syrup, stirring until completely combined. Remove from heat and stir in vanilla.
Spread the warm glaze on top of the cooled cake, and if you want to top with chocolate chips or sprinkles do it before the glaze sets.
Notes
Recipe for chocolate cake is from Allrecipes.Recipe for chocolate glaze is also from Allrecipes.