Pre-heat oven to 350 degrees Fahrenheit.
Prepare the pan: Lightly butter a 9" x 9" square metal baking pan and line the bottom of the pan with parchment paper.
To make the crust in a food processor: add flour, sugar, almond meal, and salt in the bowl of the food processor. Pulse to combine. Cut butter into small pieces and add to food processor bowl, pulse until mixture is just combined and small pieces of butter remain.
To make the crust by hand: in a large bowl, add flour, sugar, almond meal, and salt. Mix to combine. Cut butter into small pieces and add to bowl. Using a pastry cutter, a fork, or your clean hands, combine until butter is worked into flour and small pieces of butter remain.
Dump out filling into the 9" x 9" square metal baking pan and shake gently to level out the crust so it is more evenly spread on the bottom of the pan. Press the crust firmly into the corners and sides, building up 1/4" around the pan. You can use a glass or measuring cup that has a flat bottom to press the crust together if needed.
Bake filling until lightly golden, about 15-20 minutes. Remove and let cool about 10-15 minutes, until no longer piping hot.
In a stand mixer bowl, or in a bowl and using a hand mixer, beat eggs and sugar until sugar has dissolved.
Add juices, flour, and zest, and mix until combined. The top of the mixture will be foamy. Using a rubber or silicone spatula, scrape down the sides of the bowl and the bottom of the bowl and stir.
Add filling to the pan after the crust has cooled, pouring slowly to not create as many bubbles on top of the filling.
Return to oven and bake another 30-45 minutes. Depending on your oven, this will vary. The bars are done when the edges are set and center jiggles slightly, but is not still "soupy" in the middle.
To serve: Cut into 9 squares, top with powdered sugar, or some berries.