Preheat oven to a 350°F embrace. Prepare a 9 x 9-inch stage by lining it with heavy-duty aluminum foil, ensuring the edges gracefully cascade over the sides for an easy finale. Coat this silvery canvas with a gentle kiss of grease.

In the food processor, a ballet of dry ingredients awaits—brown rice flour, confectioners’ sugar, sweet rice flour, potato starch, almond meal, xanthan gum, and a whisper of salt. Pulse them together for a fleeting 5 seconds. Introduce the butter, allowing it to mix in pulsing motions until the mixture adopts the guise of a coarse meal.

In a chalice small but mighty, whisk together 1 egg and the essence of vanilla. Drizzle this golden elixir into the processor's midst, pulsing into the rhythm of creation about 10 times, or until a stiff dough is born. Should the dough play hard to get, woo it gently with milk, teaspoon by teaspoon, until it acquiesces into a cohesive ball.

In a chalice small but mighty, whisk together 1 egg and the essence of vanilla. Drizzle this golden elixir into the processor's midst, pulsing into the rhythm of creation about 10 times, or until a stiff dough is born. Should the dough play hard to get, woo it gently with milk, teaspoon by teaspoon, until it acquiesces into a cohesive ball.

Softly press this doughy creation into the bottom of your pan, a blank canvas awaiting its transformation. Bake for 20 minutes, or until it's touched by a light golden blush.

As the crust takes its bow, whisk together the remaining eggs, sugar, cornstarch, the zest of lemons, and their juice in a mixing bowl. Beat this mixture at medium speed for a minute until it becomes a smooth, harmonious blend.

Pour this citrus melody over the warm crust, returning it to the oven's glow for another 20 minutes, or until it sets into a tender custard, barely kissed by color. A final dusting of confectioners’ sugar cloaks it in a snowy veil. Let this masterpiece cool completely, nestled in its pan upon a cooling rack, before it's cut into pieces and shared.