First, make the brown butter. Add 1 cup of butter to a small saucepan on low-medium heat. Stir the butter as it melts. Once the butter melts, it will start to foam. (Don't worry this is normal!) After foaming, the butter will to a golden clear color and then start to brown. Keep an eye on the butter and stir frequently, as the butter can burn pretty quickly. Once the butter is browned, transfer to a bowl and set in the freezer. Let the butter cool until solid.
While the butter is cooling, make the base for the shortbread. Add the sugar, baking powder, salt, and blood orange zest in a bowl. Mix to combine.
Once the butter is ready, add the butter and egg to the dry ingredients. Use a pastry blender or even your hands to combine. The dough will be crumbly and dry.
Grease a 9x13 inch pan and preheat the oven to 325. Press the dough into the pan until smooth and flat. Set in the oven for about 15-20 minutes, just to set the dough.
Now for the curd. Prepare a double boiler with 1-2 inches of water. Place on high heat and wait until the water boils. Once the water comes to a boil, set it to a simmer.
Next, combine the egg yolks, granulated sugar, blood orange zest, blood orange juice, and salt in a heatproof bowl that can sit on top of a double boiler.
Whisk until the items are fully combined and then place the bowl on top of the double boiler. Continue to whisk until the mixture becomes thick, about 10 minutes. Make sure to keep a consistent whisk, or else the eggs will curdle. When the liquid thickens, it should have a texture similar to a hollandaise sauce.
Once the liquid is thick, remove it from the heat. Cut the remaining butter into small pieces and carefully insert one piece at a time. Stir until each piece is melted.
Take the shortbread out of the oven and place the curd mixture on top of the curst. Make sure it is covering all edges. Place the shortbread back in the oven for about 15 minutes, or until the curd on top is set.
Once cooled, add powdered sugar and enjoy!