heavenly chocolate cake roll

INGREDIENTS

• 6 ounces semisweet bittersweet chocolate, chopped or 1 cup semi- or bittersweet chocolate chips
• 3 tablespoons water or strong coffee
• 6 large eggs, at room temperature, separated
• 2/3 cup sugar
• 1/4 teaspoon table salt
• 2 tablespoons unsweetened cocoa powder, divided
• 1 cup heavy or whipping cream
• 2 to 3 tablespoons powdered sugar (use more if you prefer a sweeter filling)
• 1/2 teaspoon vanilla extract or 1 to 2 tablespoons liqueur of your choice, such as Grand Marnier