A Swiss roll, also called a jelly roll in the US or a roulade in France, is a thin sponge cake spread with a filling, such as jam, whipped cream, or chocolate, then rolled into a spiral and dusted with powdered sugar or cocoa.
The sponge is baked thin and flexible so it can be rolled without cracking; it's typically rolled while still warm, cooled in that shape, then unrolled to add the filling before being rerolled. Fillings range from sweet (strawberry jam, chocolate ganache) to savory (cheese, pâté).
It's popular across Europe for celebrations and as a tea-time treat, and slices can also be used as a component in trifles or ice cream cakes.