Banana walnut cake recipe

Ingredients

• 170 g plain flour
• 150 g unsalted butter
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• 4 eggs - yolks and whites separated
• 80 g sugar - divided into 2 portions
• 3 medium bananas, mashed
• 2 teaspoons lemon juice to prevent your cake from turning black the next day.
• 60ml milk
• 1/2 teaspoon cream of tartar
• 80 g walnuts, slightly chopped and toasted