Apple Spice Cake in the Crockpot

From the Recipe Shoebox. 

The Ingredients:
1 box spice cake mix (vanilla would work ok too, just add 2 tsp of cinnamon to mix)
3 eggs
1/2 c milk (oops, not pictured)
3 Tbsp oil
1/2 c sour cream (or plain yogurt)
3 large cooking apples, peeled, cored, and cut into bite size pieces
1/2 c sugar
1 tsp cinnamon
1/4 c butter, cubed and cold
1/4 c brown sugar

4-5 qt slow cooker. (smaller would make a taller cake and need to cook longer, larger would make it difficult to remove)

The Directions:

Generously grease the inside of the slow cooker.

Mix the sugar and cinnamon in a small bowl and toss with peeled, cored, and diced apples.
Place the butter along the bottom of the crock pot and then sprinkle brown sugar all over completely covering the bottom. When this cooks it will mimic a caramel sauce.
Add apples to top of brown sugar. Completely cover the bottom.
Mix together, in medium bowl, the cake mix, eggs, milk, oil, and sour cream. (I actually didn't have sour cream on hand, so I used plain yogurt and it was just fine.)
Pour batter over apples in crock pot.
Cover and cook on HIGH for 2- 2 1/2 hours. (Mine actually took 2 hours and 15 minutes in a 4 qt crock pot). You'll know it's done when a toothpick comes out clean in the center. Remove the lid, turn off the heat, and let rest for at least 15 minutes. You may want to run a knife around the edges to make sure that it will be able to come out easily.
When it is not too hot to handle (perhaps about 1/2 hour after turning off heat), then place your serving platter on top of the crock pot. Invert it so the cake will be upside down.
Gently remove the crock pot and voilà, you'll have a super moist cake with carmelized apples on top. You can serve it warm with whipped cream or ice cream, or it's just fine if you have to take it to a friend's house and then eat it an hour later as well.