Make the garnish

1. If you’re going to use the candied orange as a garnish, make a recipe of the candied orange slices.  Alternatively, you can top the bars with slivers of candied orange peel or just plain powdered sugar if you’re short on time.

Make the crust

1. Preheat the oven to 350 F (180 C). Spritz an 8 x 8 pan with a little cooking spray and then place a piece of parchment

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   that covers the bottom and two of the sides.Spray a little more on top of the parchment

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   and then place a second piece of parchment

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   that covers the other two sides.
2. Using a paddle attachment on a stand mixer, mix the powdered sugar, butter and egg yolk until just combined.
3. Add in the vanilla and the salt to the butter to combine. The mixture should be well-combined but not fluffy.
4. Pour in the flour, then pulse the mixer a few times before letting it run just long enough for the flour to disappear–about 10 seconds. Turn off the mixer, and use a baking spatula

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   to squish in any flour that’s hanging out at the bottom of the bowl.
5. Press the dough into the bottom of the pan into as even of a layer as you can get.If you have one, place a piece of plastic over the dough and use a small double sided rolling pin

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   to get into the corners.  Build up the edge of the crust to about 1/2” to 3/4” high, and make sure that the entire bottom of the pan is covered.  Be sure to inspect the bottom for any gaps between the sides of the pan and the crust.  Any gaps could cause the filling to run underneath the crust, making a soggy, sad bar.
6. Lightly poke the bottom of the crust with a fork all over the bottom.
7. Bake the crust for 20 minutes until it is set.

Add the filling

1. While the crust is baking, whisk together the filling ingredients in a small bowl.
2. Whisk together all the filling ingredients in a small bowl. Pour the filling through a fine mesh sieve

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   to get out any bits of orange pulp and sour cream.
3. Bake the filling: Pour the filling onto the hot crust after it has baked for 20 minutes. Bake for another 25-30 minutes until the center is no longer making waves of liquid when you move the pan but the center is still a little jiggly. Cut around the edges of the pan between the parchment

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   and the pan to release the bars, and then lift up the parchment

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   to set the bars on a wire rack to cool.

Finish the bars

Let the bars cool to room temperature. Just before serving, sprinkle the tops liberally with powdered sugar. Cut candied orange slices into wedges and then top the bars with 16 tiny orange wedges. Cut the cooled bars into 16 pieces. You can serve the bars at room temperature or chilled.  Serve room temperature bars immediately; otherwise, store bars in the refrigerator in a covered container for up to 5 days.