Spray 6-quart slow cooker with cooking spray. In large bowl, beat Cake ingredients with electric mixer on medium speed 2 minutes, scraping bowl occasionally. Pour into slow cooker.
In medium bowl, beat pudding mix and 2 cups cold milk with whisk about 2 minutes or until thick. Pour into slow cooker over cake batter. Do not mix. Sprinkle chocolate chips over top.
Place folded, clean dish towel under cover of cooker. This will prevent condensation from dripping down onto cake. Cover; cook on Low heat setting 3 hours to 3 hours 30 minutes or until cake is set around edges but still soft in center. Uncover, and transfer ceramic insert from slow cooker to cooling rack. Let stand 30 minutes. To serve, spoon warm cake from slow cooker. Store any remaining cake covered in refrigerator.
