1.Have eggs at room temperature.
2.Preheat oven to 240°C/475°F.
3.Pour condensed milk into medium shallow baking dish; cover with foil. Place dish in larger baking dish; add enough boiling water to large baking dish to come halfway up sides of medium dish. Bake about 1¼ hours or until milk is caramelised and golden-brown. Carefully remove caramel from oven; cool to room temperature.
4.Reduce oven temperature to 200°C/400°F. Grease 24cm x 32cm (9½-inch x 13-inch) swiss roll pan; line base and sides with baking paper, extending paper 5cm (2-inches) above long sides.
5.Beat eggs and brown sugar in small bowl with electric mixer about 10 minutes or until thick and creamy.
6.Sift flour three times.
7.Transfer egg mixture to large bowl. Pour hot milk down side of bowl; add flour and banana. Quickly fold ingredients together.
8.Pour mixture into pan; gently spread into corners. Bake about 15 minutes.
9.Place a piece of baking paper cut the same size as the pan on the bench; sprinkle evenly with white sugar. Turn cake immediately onto the sugared paper; peel away lining paper. Use serrated knife to trim edges from all sides of cake. Using paper as a guide, gently roll warm cake loosely from one of the short sides. Cool.
10.Meanwhile, whip cream until firm peaks form.
11.Whisk caramel until smooth, reserve ½ cup (save the remaining caramel for another use).
12.Unroll cake; spread with cream, drizzle with reserved caramel. Reroll cake, wrap firmly in plastic wrap; refrigerate 2 hours before serving.
Remaining caramel can be kept in an airtight container in the fridge. It will last for ages. Roll will keep in an airtight container in the refrigerator for 2 days.Note