Preheat the oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper and spray lightly with gluten-free nonstick cooking spray.
Prepare the Oatmeal Base: In a large bowl, mix the rolled oats, oat flour, coconut sugar, cinnamon, baking soda, and salt. Pour in the melted coconut oil, maple syrup, cranberries, and pistachios, and stir until the mixture becomes crumbly but sticks together when pressed.
Create the Crust: Press about ⅔ of the oat mixture evenly into the bottom of the prepared baking pan. Save the remaining ⅓ for the topping.
Make the Filling: In a separate bowl, mix the Eden Foods Apple Butter with chia seeds (if using) and vanilla extract. Spread this filling evenly over the crust.
Add the Topping: Sprinkle the reserved oat mixture over the apple butter layer, pressing lightly to adhere.
Bake: Place the pan in the oven and bake for 25-30 minutes, or until the topping is golden brown and the filling is bubbling slightly around the edges.