Preheat oven to 350ºF and line a 9x13 baking dish with parchment paper.
Mix flour, oats, brown sugar, salt, cardamon, and baking soda in a bowl. Add butter and combine with hands; mixture will be crumbly.
Press 2/3 of the flour/oat mixture evenly into the bottom of the prepared baking dish.
Mix together apple butter and applesauce. Spread apple mixture evenly on top of oat mixture; sprinkle with remaining topping.
Bake on middle rack for 25-30 minutes. Allow to cool completely in the pan on a wire rack. Store in airtight container in the fridge for up to a week. Enjoy!