Preheat oven to 350 degrees.
For the cake: Place the cake mix, sour cream, water, oil and eggs in a large mixing bowl. Blend with an electric mixer on low speed for 1 minute. Stop the machine and scrape down the sides of the bowl. Beat 2 to 3 minutes more until combined.
Pour ⅔ of the batter in a greased and floured 12 cup bundt pan.
Mix together filling ingredients. Spread filling over the batter and top with remaining batter
Bake for 45-55 minutes until the cake springs back when lightly pressed and is starting to pull away from the sides of the pan.
Cool on wire rack for 20 min, invert it onto a rack and cool 20 minutes more.
For the glaze, combine the chocolate chips and heavy whipping cream in a small saucepan over low heat. Stir until the chocolate has melted and the mixture has thickened slightly, 1 to 2 minutes.
Place the cake on a serving platter and drizzle the warm glaze over it. (I usually just melt the chips with the cream in the microwave, put the glaze in a Ziploc, cut the corner and drizzle it over the cake.)
Store cake covered in the refrigerator.