How to make a fluffy sponge cake step by step

Step 1 - preparations

• Prepare the bundt cake pan - grease it thoroughly with butter and dust with wheat flour (you can also make a simple greasing mixture - see the description below the recipe).
  
• Sift the flour through a sieve together with the baking powder.
  150 g all-purpose flour, 1 teaspoon baking powder
  
• Preheat the oven to 180℃ (top/bottom heat mode) or 170℃ (convection mode).

Step 2 - preparing the bundt cake batter

• Start lightly beating the egg whites until they are slightly fluffy.
  4 egg whites
  
• During this, add sugar and vanilla sugar, increase the mixer speed to maximum and mix for several minutes until the egg whites become very white and thick.
  170 g sugar, 15 g vanilla sugar
  
• Then add lemon juice and zest to them - mix briefly on low speed.
  juice from half a lemon, grated lemon zest
  
• Pour in the oil and mix on low speed.
  120 ml oil
  
• Add the egg yolks and mix them briefly, just until combined.
  4 egg yolks
  
• Gradually add the flour and mix on low speed just until combined - stop mixing when you can still see some uncombined flour around the edges.
  
• Then just stir the batter with a spoon.
  
• Transfer the batter to the prepared bundt pan and smooth the surface.
  

Step 3 - baking the cake

• Place the bundt cake in the preheated oven and bake for about 50 minutes - until a dry skewer comes out clean.
• After baking, remove the bundt cake and leave it on the kitchen counter for about 5-10 minutes.
• After this time, gently cut around the cake with a knife along the edges of the mold.
• Carefully turn the mold upside down and remove the cake - leave to cool completely.

Step 4 - preparing the icing

• Sift the powdered sugar into a bowl, add 1 tablespoon of milk first and mix, add more milk, and when you get a slightly runny icing, spread it over the top of the cake.
  100 g powdered sugar, approx. 2 tablespoons milk
  
• Finally, you can sprinkle the cake with grated lemon zest.