Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a medium bowl, whisk together 2 cups of all-purpose flour, 1 cup of almond flour, 1 teaspoon of baking powder, and a pinch of sea salt. Set aside.

In a large mixing bowl, cream together 1 cup of softened unsalted butter and 1 cup of powdered sugar until light and fluffy, about 3-4 minutes. Add zest of one Meyer lemon and egg yolk, mixing thoroughly.

Gradually fold the dry ingredients into the wet mixture until a soft dough forms, being careful not to over-mix.

Divide the dough into equal portions and roll each into 1-inch balls. Place on lined baking sheets with 1-inch spacing.

Bake for 18-20 minutes, rotating halfway through. Cookies are done when bottoms are light golden brown.

Let cookies cool for about 5 minutes, then roll in the remaining 2 cups of powdered sugar. Transfer to a wire rack to cool completely.