Instructions

1. Line a 9×9 baking pan with parchment, and set aside.
2. Whisk together the all-purpose flour, cake flour, cream of tartar, cinnamon, salt, baking soda, baking powder, and nutmeg together in a large bowl. Set aside.
3. Cream together the butter and brown sugar using a stand mixer fitted with the paddle attachment, ~3-4 minutes. Start off on low speed, then you can increase the speed to medium once the butter is incorporated into the sugar.
4. Add in apple butter and combine.
5. Then add the egg yolk and vanilla until combined.
6. Add in dry ingredients, gradually until ingredients are incorporated. (Do not over mix).
7. Spoon half of the dough into the prepared baking pan and press down evenly. Spread 2-3 tablespoons of apple butter on top of the first layer, if desired. Then, add the rest of the dough evenly over the top. You can place it gently on top, as if it were a crumble.
8. Chill the bars for at least 30 minutes, and as long as overnight.
9. Preheat the oven to 350°F.
10. Bake for 30-35 minutes. Allow to cool.
11. Once cooled, make the drizzle. Add the melted butter to a medium bowl and whisk in the remaining glaze ingredients until smooth, adding a splash of milk if needed to thin it out.
12. Drizzle over bars, let harden, and enjoy!