01 -
Preheat oven to 175°C (350°F). Line an 8-inch cake pan with parchment paper and lightly grease the sides.
02 -
Melt white chocolate and butter together in a microwave-safe bowl or over a double boiler until smooth, then allow to cool slightly.
03 -
In a large bowl, whisk egg yolks and granulated sugar until pale, thick, and fluffy.
04 -
Mix the melted chocolate and butter with the egg yolks and sugar mixture. Add lemon zest, pistachio flour, almond flour, and salt, blending until smooth.
05 -
In a separate bowl, beat egg whites until soft peaks form.
06 -
Gently fold the egg whites into the batter in batches using upward motions to preserve airiness, continuing until fully combined and batter is smooth.
07 -
Pour batter into the prepared pan and bake for 35–40 minutes, until the cake is set but still slightly soft in the center.
08 -
Allow the cake to cool completely in the pan before removing. Dust the surface with powdered sugar and sprinkle with chopped pistachios.