Preheat the oven and prepare the tins before you start mixing.
Grease the cake tins lightly and dust them with flour. For total peace of mind you can line the base of each tin with a circle of baking paper.
Always have the eggs at room temperature so they will reach maximum volume when you beat them.
Sift the dry ingredients together twice to aerate them.
Beat the eggs and sugar together with a wire whisk, a hand egg beater or an electric beater. (Do not use a wand blender because it cannot beat air into the eggs.)
Keep beating until the mixture is very thick and pale – at least 10 minutes. You should be able to draw a figure eight with the mixture falling off the ends of the beater in an unbroken trail.
Fold in the dry ingredients very gently with a slotted metal spoon. Steady the mixing bowl with one hand. Beginning with the edge of the spoon against the far side of the bowl, cut down through the mixture and pull the spoon gently towards you, scraping against the bottom of the bowl. When the spoon touches the near side of the bowl, rotate it slightly and lift it up, ‘folding’ the mixture up and onto itself. At the same time, give the bowl a quarter turn towards you. Keep cutting, folding and turning until everything is well combined.
When making a sponge sandwich, it is a good idea to weigh the mixture in each tin before baking to make sure the layers will be even.
When the sponge is cooked it will spring back when lightly touched with a finger and the edges will shrink slightly from the sides of the tin.
Cool the sponges in sandwich tins for 5 minutes before turning out onto a wire rack to cool.