Preheat the oven to 350ºF. Line an 8x8-inch pan with foil with enough overhang on all sides for easy removal.
In a medium bowl, combine the flour, sugar, and salt. Stir to combine. Using a pastry blender or a fork, cut in the butter until the mixture resembles coarse crumbs. Press the dough evenly into the bottom of the prepared pan. Bake for 15 to 20 minutes, or until lightly golden brown.
Filling:
While the crust cools, whisk the eggs, yolks, sugar, and salt together in a medium pot. Stir in the blood orange juice and zest. Cook over medium heat, stirring constantly, for about 10 minutes. The curd will thicken to the consistency of pudding. Stir the butter and cream into the smooth curd filling. If you want to deepen the color of the curd, add 2 drops of red and 1 drop of blue food coloring. Alternate colors and stir between each addition. Add more color if needed to achieve the desired hue. Strain the curd through a fine-mesh sieve set over a medium bowl. Pour the curd over the crust and spread evenly with a silicone spatula. Bake for 15 to 20 minutes, or until the filling is set.
Cool in pan on a wire rack for 1 hour. Cover and refrigerate for at least 2 hours. Lift the bars out of the pan using the foil overhang. Cut into 16 squares.