Preheat your oven to 350°F (175°C). Prepare a round cake pan by greasing it well and lining with parchment paper.

In a large mixing bowl, combine the eggs and sugar. Whisk until smooth, about 2-3 minutes. Add melted butter, lemon juice, lemon zest, and vanilla extract, and stir until incorporated.

Sprinkle almond flour, baking powder, and salt into the wet mixture. Fold gently until no lumps remain.

Fold in chopped pistachios, ensuring even distribution throughout the batter.

Pour the batter into the prepared pan, leveling the top. Tap gently on the counter to release air bubbles.

Bake for 45-55 minutes until edges are golden and the center is slightly jiggly. A toothpick should come out with a few moist crumbs.

For the lemon glaze, combine lemon juice and sugar in a saucepan over medium heat. Stir until sugar dissolves.

Drizzle the warm lemon syrup over the cooled cake and sprinkle additional pistachios on top. Let cool completely before slicing.