Step 1

Preheat oven to 240°C.

Step 2

Pour condensed milk in a shallow baking dish; cover with foil. Place in larger baking dish; add enough boiling water to larger dish to come halfway up sides of dish. Bake 1¼ hours or until condensed milk is golden brown. Cool to room temperature. Whisk caramel until smooth.

Step 3

Reduce oven to 180°C/350°F. Grease two deep 23cm (9-inch) round cake pans.

Step 4

Beat eggs and sugar in a small bowl with an electric mixer 10 minutes or until thick and creamy; transfer to a large bowl. Sift flour twice onto baking paper, then sift over egg mixture; fold flour, then combined butter and the boiling water into egg mixture. Spoon mixture into pans.

Step 5

Bake about 20 minutes. Immediately turn sponges onto baking-paper-covered wire racks to cool.

Step 6

Place one sponge on serving plate; spread with half the cream, drizzle with half the caramel. Top with remaining sponge, cream and caramel.