1. Make the Sponge Cake:

1. Preheat oven to 350°F (175°C). Line a 10×15-inch jelly roll pan with parchment paper and lightly grease.
2. In a large bowl, beat eggs and sugar with an electric mixer for 5 minutes, until thick and pale.
3. Mix in vanilla extract.
4. Sift flour and salt over the egg mixture; gently fold in until just combined.
5. Spread batter evenly in prepared pan.
6. Bake for 10–12 minutes, until golden and springs back when touched.
7. Dust a clean kitchen towel with powdered sugar. Immediately turn the hot cake onto the towel, peel off parchment, and roll up cake (with towel) from the short end. Cool completely.

2. Make the Caramel Sauce:

1. In a small saucepan, heat sugar over medium heat, stirring until it melts and turns amber.
2. Add butter and stir until melted.
3. Slowly stir in heavy cream and salt (it will bubble up). Stir until smooth.
4. Remove from heat and cool to room temperature.

3. Prepare the Filling:

1. Whip heavy cream and powdered sugar to stiff peaks.

4. Assemble the Roulade:

1. Carefully unroll the cooled cake.
2. Spread whipped cream evenly over the cake, leaving a ½-inch border.
3. Drizzle with caramel sauce (reserve a little for topping).
4. Arrange banana slices over the cream.
5. Gently roll up the cake (without the towel). Place seam-side down on a platter.

5. Serve:

1. Dust with powdered sugar and drizzle with remaining caramel sauce.
2. Slice and enjoy!