How to make pistachio sponge cake step by step

Step 1 - preparations

• Line the bottom of the baking pan with parchment paper, leaving the sides empty and dry.
• Preheat the oven to 180 degrees Celsius (top-bottom heat) or 170 degrees Celsius (fan-forced).

Step 2 - grind pistachios

• Grind the pistachios in a food processor or grinder into a fine powder.
  120 g pistachios
  

Step 3 - prepare the sponge cake

• Sift both flours and baking powder through a sieve.
  150 g wheat flour - all-purpose, 30 g potato starch, 1 teaspoon baking powder
  
• Add the ground pistachios to the flour and mix together.
  
• Beat the egg whites with sugar until they are white and very fluffy - I beat for a few minutes on high speed with a mixer.
  6 egg whites, 170 g sugar
  
• Add the egg yolks to the egg whites and mix on low speed, or gently fold in with a whisk.
  6 egg yolks
  
• Add the sifted dry ingredients to the eggs and gently mix just until combined.
  

Step 4 - bake the pistachio sponge cake

• Transfer the sponge cake batter to the prepared pan and smooth the surface.
  
• Place the pan with the sponge cake in the preheated oven and bake for about 45-50 minutes - until a skewer comes out clean.
• After baking, let the sponge cake cool completely before removing it from the pan.