Lightly grease a 6 to 8 quart slow cooker with non-stick cooking spray.
In the bowl of your mixer, combine the cake mix, water, vegetable oil, eggs, pumpkin puree, brown sugar and pumpkin pie spice. Beat on low speed for 30 seconds, then medium speed for 2 minutes.
Pour cake mix into prepared slow cooker.
In a separate bowl combine the pudding mix and milk and whisk for 2 minutes. Pour the pudding over the cake batter in the slow cooker then sprinkle the chocolate chips evenly over the top.
Cover and cook on HIGH for 2 1/2 to 3 hours, or until a toothpick inserted in the center comes out with moist crumbs. The pudding should be slightly bubbling out the sides of the cake.
Turn the heat off of the cake and let it sit for about 10 minutes before serving. Serve with ice cream or whip cream on top. Enjoy!