Caramel Coffee Buttercream Cake 焦糖咖啡黄油奶油蛋糕 Gâteau crème au beurre et au café caramel

Ingredients Coffee sponge cake Baking pan of 40cm x 30cm 3 eggs Sugar 100g Cake flour 80g Espresso 15g Milk 25g 180°C (356°F) for 10 minutes Coffee battercream Sugar 30g Water 10g Liquid cream 50g Espresso 50g 1 egg Sugar 100g Softened unsalted butter 300g