Preheat oven to 350 degrees. Prepare a 9x13 baking dish with non-stick spray. You can line the pan with foil and spray the foil if you prefer, this makes the bars easier to remove.
Base
In a large mixing bowl, combine the cake mix, egg and butter and mix until a firm dough is formed. Press into the bottom of your prepared baking dish and set aside.
Cheesecake Layer:
Using a food processor, add the sweet potatoes, cream cheese, sugar, egg and spices and pulse the mixture until it’s nice and creamy. Pour over the base in your prepared pan. Bake this for 23-25 minutes until the cheesecake is set.
Topping:
Once the cheesecake is done baking, prepare the creamy and crumbly topping.
In a small bowl, mix the greek yogurt, vanilla and sugar together. Spread this over the baked cheesecake.
In a small bowl, add the crumble topping ingredients, mix together and then sprinkle it all over the top of your creamy topping layer. Bake for another 5 minutes. Allow the cheesecake bars to cool and then refrigerate for several hours, preferably overnight if you can.