• 6 egg whites
• 1 pinch salt
• 1 tablespoon lemon juice
• 1 level teaspoon cream of tartar
• 150 g (5½ oz) caster (superfine) sugar
• 1 teaspoon natural vanilla extract
• 60 g (2¼ oz) plain (all-purpose) flour
• Diced pineapple and strawberries, to decorate (optional) whipped cream, to serve (optional)

TAKE A ROUND CAKE TIN, 22 CM (8½ INCHES) IN DIAMETER WITH 10 CM (4 INCH) HIGH STRAIGHT SIDES, AND LINE IT WITH BAKING PAPER. Be careful not to butter the tin or use a silicone mould, or you could ruin the cake: it will have trouble rising because the batter won’t stick to the side of the tin. (Alternatively, use two smaller cake tins and check the cakes are ready a little earlier when cooking.)

PREHEAT THE OVEN TO 190°C (375°F/GAS 5). Using an electric beater, beat together the egg whites, salt and a few drops of lemon juice, until they are frothy, without being too firm.

ADD THE CREAM OF TARTAR AND BEAT AGAIN UNTIL THE WHITES START TO HOLD THEIR SHAPE. Gently incorporate the sugar, beating at the same time for about 2 minutes. Next, add the vanilla extract and mix everything together well.

ONCE THE EGG WHITES ARE QUITE FIRM AND GLOSSY, GENTLY SIFT THE FLOUR OVER THE TOP AND FOLD IT IN GRADUALLY WITH A LARGE SPOON OR FLEXIBLE SPATULA. ‘Slice’ the egg whites in two and lift up to gently incorporate the flour.

POUR THE BATTER INTO THE TIN AND BAKE FOR 35–40 MINUTES. The surface of the cake should be golden and rounded (the top of the cake should spring back when you press it lightly with your finger).

TAKE THE CAKE OUT OF THE OVEN AND RUN A KNIFE AROUND THE SIDE OF THE TIN TO UNMOULD IT MORE EASILY. Turn the tin over onto a plate and let it cool for 10 minutes before unmoulding the cake completely.

SERVE THE CAKE WITH DICED PINEAPPLE AND STRAWBERRIES, AND WHIPPED CREAM IF YOU LIKE.