Prep time30 minutes, plus chilling
Cook Time40 to 45 minutes
1 cup (2 sticks/225 g) unsalted butter, at room temperature
½ cup (98 g) granulated sugar
1½ cups (180 g) all purpose flour
½ cup (50 g) cocoa powder
½ teaspoon kosher salt
1 cup (198 g) granulated sugar
1 tablespoon (8 g) cornstarch
1 cup blood (238 g) orange juice
¼ cup (60 g) lemon juice
3 large eggs plus 3 egg yolks (approx. 222 g total) at room temperature
½ cup (1 stick/112 g) unsalted butter, softened and cut into cubes
Zest of two blood oranges (approx. 30 g)
A drop or two of red food coloring (optional)
Make the crust:
Preheat the oven to 325℉ (160℃).Lightly butter an 8x8 inch baking pan and line with a Kana Easy-Lift Parchment Paper Square. Set aside.
In a large bowl, cream together butter and sugar until pale in color and fluffy, about 3-4 minutes.Stir in the flour, cocoa powder and salt until a soft dough forms. Press the dough into an even layer with your hands, then smooth with a spatula.Bake for 20-25 minutes, until the top is set.
Make the filling:
Stir together the sugar and cornstarch for the filling with a fork until well combined and lump-free.
Combine blood orange and lemon juices in a Mini Milo Dutch Oven over medium-low heat. Add the sugar-cornstarch mixture and stir until the liquid is hot (but not boiling) and the sugar is dissolved. Turn the heat down to the lowest possible setting.
In a medium bowl, whisk together the eggs and egg yolks until well blended and no traces of egg white appear unmixed. Take a small amount of the hot liquid and carefully pour into the eggs to temper them, stirring to prevent the eggs from cooking.Gently stream the warmed egg mixture into the hot juice mixture, whisking constantly. It will turn more orange in color from the yolks; the red food coloring (if using) will return the color to a pink hue in the next step.
Switch to a rubber spatula and stir the mixture constantly over low heat. Once the mixture comes to a boil, allow it to bubble for a full minute, stirring constantly, then remove from the heat. Stir in the butter, then food coloring, if desired.
Strain the filling over the hot crust and smooth into an even layer. Sprinkle the zest over the top and bake at 325℉ (160℃) for an additional 20-25 minutes, until the top is set and the filling is jiggly, but not completely liquid.Cool on a rack for at least 30 minutes, then cover and place in the refrigerator for at least 4 hours, or overnight.
Run a knife around the edge of the pan to loosen the bars, then use the handles on the Kana Easy-Lift Parchment Paper Square to remove the bars from the pan.Cut into 16 2-inch squares (or the size of your choosing) and serve.