Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan, lining the bottom with parchment paper.

In a large mixing bowl, combine the ricotta cheese and granulated sugar, mixing until smooth and creamy. Add eggs one at a time, mixing well.

Stir in melted butter, lemon zest, lemon juice, and vanilla extract, folding gently.

In a separate bowl, whisk together all-purpose flour, baking powder, and salt. Gradually add to the wet ingredients, stirring gently.

Fold in chopped pistachios gently, being careful not to overmix.

Pour the batter into the prepared cake pan, smoothing the top.

Bake for 30-35 minutes, until golden brown and a toothpick comes out clean.

Cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Dust with powdered sugar before serving.