Spray slow cooker crock with cooking spray and set aside.
In a large bowl, combine the cake mix, water, eggs, and oil; beat on low speed for 30 seconds. Beat on medium for 2 minutes. Transfer to prepared slow cooker crock.
In another bowl, whisk milk and pudding mix for 2 minutes. Let stand for 2 minutes or until soft-set. Spoon over cake batter; sprinkle with pumpkin spice morsels. Cover and cook on high for 3-4 hours or until a toothpick inserted in the cake portion comes out with moist crumbs. Serve warm.
Notes
This technique works for any flavor of cake you'd like to make. Try swapping out all of the pumpkin for chocolate!