Ingredients:

  • For the Chocolate Sponge (jelly roll):
  • 4 large eggs (about 200 g without shells)
  • 3/4 cup (150 g) granulated sugar
  • 1 tsp (5 ml) pure vanilla extract
  • 3/4 cup (95 g) cake flour, sifted
  • 1/4 cup (25 g) unsweetened cocoa powder, sifted
  • 1/8 tsp fine salt
  • 2 tbsp (30 ml) neutral oil (vegetable or grapeseed) — optional
  • 2 tbsp (15–20 g) powdered sugar or unsweetened cocoa powder (for dusting a towel)
  • For the Chocolate Ganache Filling:
  • 6 oz (170 g) semi-sweet chocolate, finely chopped (or chips)
  • 1/2 cup (120 ml) heavy (double) cream
  • 1 tbsp (14 g) unsalted butter (optional)
  • 1–2 tbsp (8–16 g) powdered sugar, optional
  • For Finish:
  • Additional cocoa powder or powdered sugar, for dusting
  • Chocolate shavings or melted chocolate (optional)

Instructions:

  1. Preheat oven to 375°F (190°C). Line a 10 x 15 inch (25 x 38 cm) jelly roll pan with parchment, leaving an overhang; lightly grease the parchment.
  2. In a large bowl combine 4 large eggs, 3/4 cup granulated sugar, and 1 tsp vanilla. Whisk with an electric mixer at medium-high until thick, pale, and ribbon-like (about 5–8 minutes).
  3. Sift together 3/4 cup cake flour, 1/4 cup cocoa powder, and 1/8 tsp salt. Gently fold the dry mixture into the whipped eggs in 2–3 additions using large, gentle strokes to retain aeration. Fold in 2 tbsp oil if using until just combined.
  4. Spread the batter evenly into the prepared pan in a thin layer using an offset spatula. Smooth the top and bake 10–12 minutes until sponge is springy and set but not dry or deeply browned.
  5. Immediately dust a clean kitchen towel with powdered sugar or cocoa. Turn the warm cake out onto the towel, peel off the parchment, and starting at one short end roll the cake and towel together into a tight spiral. Allow to cool completely while rolled.
  6. Make the ganache: heat 1/2 cup cream until just simmering, pour over 6 oz chopped semi-sweet chocolate in a heatproof bowl. Let sit 1–2 minutes, then stir until smooth. Stir in butter and powdered sugar if using. Cool until spreadable.
  7. Carefully unroll the cooled cake. Spread an even layer of ganache leaving a 1/2-inch (1 cm) border. Re-roll the cake without the towel, using the parchment overhang if helpful. Wrap in plastic and chill at least 30–60 minutes to set.
  8. Trim the ends for clean slices. Dust with cocoa or powdered sugar and add chocolate shavings if desired. Slice with a sharp serrated knife, wiping the blade between cuts for neat slices.