For the Sponge Cake

• 4 large eggs, at room temperature
• ¾ cup granulated sugar
• 1 teaspoon vanilla extract
• ¾ cup all-purpose flour
• 1 teaspoon baking powder
• ¼ teaspoon salt

For the Banana Chocolate Filling

• 2 ripe bananas, mashed smooth
• 1 cup heavy whipping cream, cold
• 2 tablespoons powdered sugar
• ½ teaspoon vanilla extract
• ½ cup chocolate spread or melted semi-sweet chocolate

Optional Finishing Touches

• Powdered sugar for dusting
• Melted chocolate or chocolate drizzle
• Fresh banana slices (for serving only)

The key to this recipe is balance. The sponge cake must remain flexible and tender, while the filling should be creamy but stable enough to hold its shape when rolled.