Coat a 4-quart slow cooker with cooking spray then turn on high.
In a mixing bowl, combine flour, baking powder, baking soda, salt, pumpkin pie spice, and cinnamon.
In a large bowl, beat sugars and butter with an electric mixer for about 3 minutes, then add eggs, one at a time, mixing well after each one. Add pumpkin, blend until well combined.
Gradually add flour mixture and beat at low speed for a minute or so until smooth. Spread evenly in prepared slow cooker.
Cover and cook on high 2 hours or until a toothpick in the center comes out clean.
Let cake stand, uncovered 10 minutes.
Invert onto wire rack, invert again onto serving plate.
Drizzle half of caramel sauce over cake. Serve warm with additional sauce.