Preheat oven to 350°F (177°C). Lightly grease and line a 9 x 9-inch baking pan with parchment paper, leaving an inch or two overhangs on all sides for easy removal.
In a large bowl, whisk together the flours, cream of tartar, cinnamon, baking soda, salt, and baking powder until thoroughly combined.
In the bowl of a stand mixer fitted with the paddle attachment, beat together melted butter, the Redpath® Golden Yellow Sugar, and the Redpath® Granulated Sugar until well mixed and butter has completely cooled; 2 minutes.
Add the egg and incorporate it completely before adding the yolk and vanilla extract. Beat well after each addition.
Add half of the dry ingredients into the bowl, and mix on low speed until just combined. Repeat the process with the remaining dry ingredients until no flour streaks remain, and a dough is formed.
Transfer the dough to the prepared baking pan. Press and spread into an even layer.
Place into the fridge to chill and allow the flour to hydrate; at least 30 minutes.
In a small bowl, whisk together the Redpath® Granulated Sugar and cinnamon, until cinnamon is evenly distributed throughout the sugar. Whisk in the Redpath Simply Raw™ Turbinado Sugar.
Remove chilled bars from the fridge. Evenly sprinkle the cinnamon sugar topping over the surface of the dough.
Place into the preheated oven and bake for 25 to 30 minutes. Bars are done when the edges are slightly puffed and the surface in the middle is dull and just set, and a skewer inserted into the centre of the pan comes out with a few moist crumbs attached.
Remove from oven and allow to cool completely on a wire cooling rack.
Carefully remove the snickerdoodle using the parchment paper overhangs and transfer to a cutting board.
With a sharp chef’s knife or serrated bread knife, slice the snickerdoodle into bars.
Store completely cooled snickerdoodle cookie bars in an airtight container layered between parchment paper at room temperature or in the fridge for up to a week. Wrapped well, they can be stored in the freezer for up to 3 months.
*If bread flour is unavailable, using only all-purpose flour will work, too, though the chewiness will not be as pronounced.
*Ensure all ingredients are at room temperature unless otherwise stated before proceeding with the recipe.
*If already made, use ¼ cup of one of these sugars from the recipe, “Cinnamon Sugars”, instead of making the topping as listed in this recipe.
*Redpath® Dark Brown Sugar can be substituted for the Redpath® Golden Yellow Sugar. Note that the resulting bars will be darker in colour and have more of a noticeable caramel flavour undertone.