Gluten-free white sponge cake

Ingredients:

• 450g all-purpose gluten-free flour mix, recipe below
• 1 teaspoon psyllium (optional)
• 4 tsp baking powder
• 0.5 tsp salt
• 1 cup of milk
• 1 tsp vanilla extract
• 220 g unsalted butter, room temperature
• 1.5 cups of sugar
• Whites of 8 large eggs, room temperature
• 0.5 tsp cream of tartar
• 1/3 cup sugar

All-purpose gluten-free flour mix

• 400 g of millet flour
• 300 g sweet (glutinous) rice flour
• 300 g potato starch

Preparation:

1. Preparation:

   
   Preheat oven to 190°C. Line two 22cm cake pans with greased parchment paper.
   

2. Mix dry ingredients:

   
   In a bowl, combine gluten-free flour mixture, psyllium husk, baking powder and salt.
   

3. Mix the liquid ingredients:

   
   Mix milk with vanilla extract in a bowl.
   

4. Beat butter and sugar:

   
   Place the butter in a mixer bowl. Beat until smooth. Add the sugar. Beat until the sugar is completely dissolved in the butter and the mixture is smooth.
   

5. Dough:

   
   With the mixer on low speed, add a third of the dry mixture. Once it's completely incorporated, add half of the milk mixture. Repeat, finishing with the dry mixture. Carefully transfer the cake batter to a large bowl.
   

6. Egg whites:

   
   Wash the mixer bowl and dry it thoroughly. Add the egg whites. Turn on the mixer with the whisk attachment. Add the cream of tartar to the whites. Beat until the whites turn white and begin to thicken. Add the sugar and continue beating until soft peaks form.
   

7. Fold the whipped egg whites into the batter:

   
   Fold one-third of the whipped egg whites into the batter. Using a silicone spatula, fold the egg whites in slowly and steadily. When no more egg whites remain, add another third. Continue folding until the batter is light and fluffy. Once you've folded in the last portion of whipped egg whites, stop mixing the batter.
   

8. Baking the cake:

   
   Divide the batter evenly between the two prepared pans. Place in the oven and bake until the top springs back slightly when pressed and a toothpick inserted into the center comes out clean, 30-40 minutes.
   
9. Let the cakes cool in the pans. Run a knife around the edges of the pan to loosen the cakes. Carefully invert the cakes onto wire racks.

10. All-Purpose Gluten-Free Flour Mix:

    
    Pour all the flour into a large container. Large plastic containers are available in the restaurant supply section and are suitable for this purpose. A large glass jar will also work. Shake the container until all the flour is combined and uniform in color.