Marbled Chocolate Cheesecake 云石巧克力芝士蛋糕

Ingredients : 250g cream cheese (奶油芝士 60g caster sugar (细砂糖) 1 egg (鸡蛋) 1 tsp lemon juice (柠檬汁) Chocolate cake : 180g butter (牛油) 130g caster sugar (细砂糖) 1/4 tsp salt (盐) 3 eggs (鸡蛋) 120g plain flour (普通面粉) 20g cocoa powder (可可粉) 1/4 tsp baking powder (发粉)