In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugars together until light and fluffy, about 3 minutes. Scrape down the sides of the bowl to ensure even mixing.

Add the egg and vanilla extract, mixing until well combined. Scrape down the sides of the bowl again.

In a separate bowl, whisk together the flour, baking powder, cinnamon, and salt.

Gradually add the dry ingredients to the wet ingredients and mix just until the dough begins to pull away from the sides of the bowl. Be careful not to overmix.

Set aside about 2 cups of the dough (loosely packed) to use for the top crumble.

Press the remaining dough evenly into an 8 x 8-inch baking pan lined with parchment paper. Use your hands or the flat side of a measuring cup to press the dough into the corners and smooth it out.

Bake at 350°F for 15 minutes, or until the edges are lightly golden and the center is just set. Do not overbake.

Remove the pan from the oven and let the crust cool slightly while you prepare the cranberry filling.

In a large bowl, mix together the cranberries, sugar, cornstarch, orange zest, orange juice, and vanilla extract. Pour this cranberry mixture over the pre-baked crust.

Use your hands to break up the reserved 2 cups of shortbread dough into smaller, flat pieces. Scatter them randomly over the cranberry filling, leaving spaces for the cranberries to peek through.

Bake for about 45 minutes, covering the top of the pan with aluminum foil for the last 10 to 15 minutes to prevent the crumble from becoming too dark.

Remove the bars from the oven and place the pan on a wire rack to cool completely before adding the vanilla glaze.

Vanilla Glaze

Whisk together the powdered sugar, milk (or heavy cream), and vanilla extract. 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 it’s too thin, add more powdered sugar. Drizzle the glaze over the cooled bars before serving.