Pan di Spagna (Italian sponge)

Step 1: Heat the oven to 350°F (fan 300°F). Grease and flour the sides of a 22 cm round tin and line the base with baking paper.

Step 2: Whisk 5 eggs, 5 ½ oz caster sugar, 1 tsp vanilla extract and 1 tsp lemon zest with an electric mixer on high for 12–15 minutes. Don't cut this short: under-beaten eggs are the most common reason a pan di Spagna comes out flat. It is ready when it is pale, thick and has at least tripled, and a ribbon from the whisk holds on the surface for 5 seconds.

Step 3: Sift 3 ½ oz plain flour and 1 ¾ oz potato starch together three times, then sift them over the foam in three lots, folding gently from the bottom up with a large spatula until no dry pockets remain.

Step 4: Pour into the tin and bake for 35–40 minutes without opening the oven, until risen, golden and springy, and a skewer comes out clean.

Step 5: Turn the oven off, prop the door open and leave the sponge inside for 10 minutes, then turn it out upside down onto a rack and cool completely, ideally overnight wrapped in cling film; it slices more neatly the next day.

Step 6: Warm ½ cup orange juice with 2 tbsp caster sugar for 1 minute until dissolved, then cool. Split the sponge into 2 or 3 layers with a long serrated knife and brush each cut side with the syrup before filling with custard, cream or fruit. A filled cake keeps in the fridge for 2 days.