Preheat the oven to 350 degrees F (180 degrees C).
In a standing mixer with a paddle attachment, combine Granulated Sugar (1/4 cup), Vanilla Extract (1 teaspoon), and Butter (1 cup) until it starts to turn pale.
Add the All-Purpose Flour (2 cup) one cup at a time, and continue to mix on low until it starts to combine.
Turn off the mixer and using a silicone spatula, fold the dough together until it forms a ball.
Place dough on a 9x13-inch cookie sheet (at least 1 1/2 inches deep) or casserole dish, and press the dough out until it covers the entire sheet.
Bake for 18 minutes. Take our the crust but leave the oven on.
In a large mixing bowl, whisk together Egg (6), Granulated Sugar (3 cup), Blood Orange Juice (3/4 cup), Lemon Juice (1/4 cup) and 1 Tbsp zest from the Lemon (1) until smooth.
Add the All-Purpose Flour (1 cup) and continue to whisk for 2 minutes.
Pour mixture into the crust and bake for another 30-35 minutes.
When the time is up and the bars look set and firm, remove from the oven and let stand at room temperature for 30 minutes.
Then, refrigerate for 1-2 hours.
Dust with Powdered Confectioners Sugar (to taste). Add in beet powder or hibiscus powder to the powdered sugar to add color if desired. Cut into squares.