Japanese shortcake jelly roll with chocolate whipped cream

Ingredients

For the cake:

• 4 large eggs, separated, at room temperature
• 120 g granulated sugar, sifted, divided
• 3 tablespoons whole milk, at room temperature
• 1 teaspoon vanilla
• 120 g cake flour, sifted 3 times
• 22 grams butter, melted and cooled slightly

For the whipped cream:

• 1 cup heavy whipping cream, cold
• 3 tablespoons powdered sugar
• 1 tablespoon Dutch-processed cocoa powder
• 1/2 teaspoon dry gelatin
• 1 tablespoon cold water
• 1/2 cup seedless strawberry jelly, at room temperature
• Powdered sugar, for garnish
• Cocoa powder, for garnish