Preheat your oven to 350°F (175°C).
Grease a 9-inch round cake pan with butter or cooking spray and line the bottom with parchment paper.
In a large mixing bowl, combine almond flour, granulated sugar, baking powder, and salt.
In a separate bowl, whisk together melted butter, eggs, fresh lemon juice, and lemon zest.
Pour the wet ingredients into the dry ingredients and gently stir until just combined.
Pour the batter into the prepared cake pan and smooth the top. Bake for 25-30 minutes until set.
Let the cake cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.