For making the top layer with black chocolate and butter, I follow the method in this video https://youtu.be/bulnxOtFPiM Ingredient (I only use half of the quantity in the video) Black chocolate 125g Butter 100g Brown sugar 25g Milk 1/2 tbsp Vanilla extract 1/4 tsp Tips: After melting black chocolate in the butter, put the mixture in the fridge. Need to check it after 15 minutes. Don’t leave it in the fridge for too long, otherwise the mixture will become solid which is undesirable. For the Swiss roll, I just use this recipe https://bakingtaste.blogspot.com/2018/12/chocolate-swiss-roll.html