Line a slow cooker (4 quart or larger) with parchment paper. Liberally spray the parchment paper lining with nonstick spray.
In a large mixing bowl, combine the cake mix, 1 1/4 cups milk, oil and eggs. With an electric mixer, mix on low for 1 minute. Increase the speed to medium, and continue to mix for 2 - 3 minutes or until the batter is smooth and glossy. Pour the cake batter into the prepared slow cooker.
In a medium bowl, combine the pudding and 2 cups milk. With an electric mixer, beat on medium-low for 3-4 minutes or until the pudding thickens. Pour the pudding over the cake batter. Do not stir.
Sprinkle the chocolate chips over the pudding. Do not stir.
Put the lid on top of the slow cooker. Cook on low for 2 1/2 hours or until the top of the cake is set.
Serve in individual bowls with vanilla ice cream!