For the Chocolate Sponge:
- ½ cup (60g) flour (I used cake flour, but all-purpose flour works too)
- 3 tbsp (30g) unsweetened cocoa powder
- 1 tbsp (10g) cornstarch
- a pinch of salt
- 2 tbsp (30ml) boiling water
- 2 tbsp (30ml) vegetable oil
- 4 eggs (about 240g)
- ½ cup (120g) sugar
Baking Temperature: 350°F (180°C).
Baking Tips:
- Preheat your oven before you start.
- Baking time depends on the thickness of the batter. I used a 16x15 inch (or 40x38 cm, external dimensions) baking tray, and it took 12 minutes for the sponge to bake perfectly. If your baking tray is smaller, the batter will be thicker, so you may need to bake it a bit longer. Be careful not to overbake—start checking for doneness after 10-12 minutes by inserting a toothpick into the center. It should come out clean. Avoid opening the oven during the first 10 minutes to prevent the sponge from deflating.
- Don’t use a small baking tray, as the batter layer will be too thick, making it harder to roll the sponge later.
- Roll the sponge cake immediately after taking it out of the oven while it’s still hot and flexible. Once it cools, it won’t roll as easily.
For the Chocolate Ganache:
- 7 oz (200g) dark chocolate
- 1 ¼ cups (300ml) heavy cream
Ganache Tip: use a 1:1.5 ratio of chocolate to heavy cream for a silky, spreadable ganache. If you prefer a thicker consistency, go with a 1:1 ratio.