Line 2 baking sheets with parchment paper or silicone baking mats and set aside.
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.
2 cups all purpose flour, 2/3 cup cake flour, 1 1/2 tsp. cream of tartar, 1 1/2 tsp. cinnamon, 1 tsp. salt, 1 tsp. baking soda, 1/2 tsp. baking powder, 1/2 tsp. nutmeg
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. 12 Tbsp. unsalted butter, cold, cut into cubes, 1 1/4 cup dark brown sugar, packed
Add in apple butter and combine.
1/3 cup apple butter (I used store-bought), 1 large egg yolk, 2 tsp. vanilla extract
Then add the egg yolk and vanilla until combined.
Add in dry ingredients, gradually until ingredients are incorporated. (Do not over mix).
Using a 2 Tbsp. cookie scoop, scoop the dough and drop onto a plate or baking sheet (be sure there is room in the fridge if using a baking sheet). Chill the scooped dough balls for 30 minutes – 1 hour or up to overnight.
Mix the granulated sugar and cinnamon in a small dish.
2 Tbsp. sugar, 1 tsp. cinnamon
Preheat the oven to 350°F. Drop the chilled cookie dough balls in the cinnamon sugar mixture, tossing to coat all sides. Place on the prepared baking sheet.
Bake for 10-11 minutes. Cookies will be very soft and puffy at first, allow to cool on the pan for an additional 10 minutes, then move to a cooling rack to cool completely.
Once cooled, make the glaze. 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.
2 Tbsp. unsalted butter, melted, 1 cup powdered sugar, 2 Tbsp. apple butter, 1/2 tsp. vanilla extract, pinch of salt
Drizzle over cookies, add a sprinkle of any leftover cinnamon sugar on top of the glaze if desired, and enjoy!