Line a slow cooker with parchment paper or a liner.
In a large mixing bowl, combine cake ingredients and mix until fully combined.
Spread batter into slow cooker. Secure a paper towel under the lid of the slow cooker.
Cover and cook on high for 1 hour 45 minutes to 2 hours or until toothpick inserted comes out clean.
Remove crock from slow cooker and let cake cool 10 - 15 minutes. Then lift cake out of slow cooker and cool completely before frosting.
Meanwhile, mix cream cheese, butter, vanilla and powdered sugar together until fully combined and fluffy. Spread this over the cake after it has cooled completely.
Top cake with chopped walnuts and serve with a drizzle of caramel sauce, if desired.