Preheat your oven to 180°C (350°F) and line the baking tray with parchment paper.

In a mixing bowl, beat the eggs and sugar together using an electric mixer until the mixture is thick and pale, about 5 minutes.

Sift the flour, baking powder, and salt together into the egg mixture. Gently fold using an offset spatula until well mixed.

Pour the batter into the prepared baking tray, spreading it evenly. Bake in the preheated oven for 12-15 minutes, or until golden brown.

While the cake is baking, prepare the caramel by melting the sugar over medium heat until it turns a golden color.

Once the sugar is golden, remove from heat and stir in the butter until melted, then slowly whisk in the heavy cream until smooth. Let it cool for a few minutes, then stir in the vanilla extract.

Remove the cake from the oven and let it cool slightly in the tray. Once cool enough to handle, invert the sponge onto a clean kitchen towel sprinkled with sugar and carefully peel off the parchment paper.

Spread the mashed bananas over the sponge cake evenly. Roll the cake tightly from the short end, using the towel to help. Wrap it in plastic wrap and refrigerate for 30 minutes.

After chilling, unwrap the roulade and slice it with a sharp knife. Drizzle the caramel sauce over each slice before serving.