Preheat oven to 350℉.
In a large bowl, cream together the nut butter and sugar using a hand mixer until it's light and fluffy. Scrape down the sides of the bowl.
Add in the eggs, vanilla, maple syrup and salt. After that is mixed slightly, add in the baking soda and cassava flour (baking powder/cream of tartar for paleo option)
Cut the apples into slices. Place into a small bowl.
Add ¼ teaspoon of cinnamon and 1 tablespoon of maple syrup to the apples. Toss to coat the apples and then layer them along the bottom of a greased 9" cake pan with coconut oil.
Pour the batter over the apples and spread it out evenly over them. Bake for 20-25 minutes or until toothpick comes out clean.