1. In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugars until light and fluffy, about 3 minutes. Scrape down the sides of the bowl.
2. Add the egg and vanilla, mixing to combine well. Scrape down the sides of the bowl.
3. In a separate bowl, whisk together the flour, baking powder, cinnamon and salt.
4. Add the dry ingredients and mix just until the dough starts to pull away from the sides of the bowl. Do not over mix.
5. Set aside roughly 2 cups of the dough (losely packed) and reserve to use on the top of the crumble.
6. Press the shortbread dough into the an 8 x 8 baking pan lined with parchment paper. Use your hands or the flat side of a measuring cup to press it evenly into the corners of the pan.
7. Bake at 350°F for 15 minutes, or until the edges are slightly golden brown and the center is just set. Do not over bake.
8. Remove the pan from the oven and allow the crust to cool slightly while you make the cranberry filling.
9. In a large bowl, mix together the cranberries, sugar, cornstarch, orange zest and juice and vanilla. Pour the cranberry mixture over the pre-baked crust.
10. Use your hands to break up the remaining 2 cups of shortbread dough into smaller, flat pieces. Place them randomly on top of the cranberry filling, leaving space between them for the cranberries to peak through.
11. Bake for about 45 minutes, covering the top of the pan with aluminum foil for the last 10 to 15 minutes of baking time so that the crumble does not turn too dark.
12. Remove the bars from the oven. Place the pan on a wire rack and cool completely before adding the vanilla glaze.

Vanilla Glaze

Whisk together the powdered sugar, milk (or heavy cream) and vanilla. The glaze should be thin enough to run off a fork but not so thin that it’s transparent. If the glaze is too thick, add more milk. If too thin, add more powdered sugar. Drizzle over the top of the bars once cooled.

Slice into squares.