Preheat the oven to 350 degrees.

|| Crust || In a standing mixer with a paddle attachment, combine sugar, vanilla, and room temperature butter until it starts to turn pale. Add the flour 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 9″ x 13″ cookie sheet (at least 1 and 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.

|| Filling || Whisk together eggs, sugar, blood orange juice, lemon juice, and lemon zest until smooth. Add the flour and continue to whisk for two 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 one to two hours.

Dust with powdered sugar. Add in beet powder or hibiscus powder to the powdered sugar to add color if desired. Cut into squares.