Chocolate Swiss Roll Cake

Chocolate whipped cream

110g milk chocolate 54.5% (couverture)
110g heavy cream (to melt the chocolate)
350g cold heavy cream

Chocolate Frosting

unsalted butter room temperature 400g
cocoa powder 50g
dark chocolate 130g melted
¾ teaspoon salt
1 ½ teaspoons vanilla extract
powdered sugar sifted 720g
heavy cream 120ml