Steps

1. Prepare a 15cm (6-inch) round springform pan.
   🕒 00:22
2. Line the bottom and sides of the pan with parchment paper.
   🕒 00:28
3. Sift together 20g Cake Flour and 10g Cocoa Powder for the brownie batter. **Key Tip:** Sifting prevents lumps and ensures an even mix. Sift 2-3 times to thoroughly combine the dry ingredients.
   🕒 00:34
4. Sift 5g Cake Flour for the cheesecake batter.
   🕒 00:34
5. Combine 100g Bittersweet Chocolate (67%) and 50g Heavy Cream. Heat in the microwave at 600W until melted.
   🕒 01:05
6. Stir the melted chocolate and heavy cream until smooth. Reheat if any chocolate remains unmelted.
   🕒 01:17
7. Add 40g Granulated Sugar and mix well.
   🕒 01:33
8. Add 1 egg and mix thoroughly until smooth, even if the mixture appears a bit lumpy.
   🕒 01:53
9. Add all of the sifted dry ingredients for the brownie batter (20g Cake Flour, 10g Cocoa Powder) at once. Gently mix until no dry streaks remain.
   🕒 02:21
10. Pour the brownie batter into the prepared pan and spread evenly with a rubber spatula.
    🕒 02:49
11. Soften 200g Cream Cheese with a rubber spatula. **Key Tip:** Hard cream cheese can lead to failure. If it's too hard straight from the fridge, microwave for 5-10 seconds (be careful not to melt it completely).
    🕒 03:03
12. Add 50g Granulated Sugar to the softened cream cheese and mix well.
    🕒 03:36
13. Add 2 eggs all at once and beat until well combined.
    🕒 03:51
14. Add the sifted 5g Cake Flour for the cheesecake batter and mix until no dry ingredients are visible. **Key Tip:** Even a small amount of flour significantly impacts the final texture, so it's essential to add it.
    🕒 04:19
15. Add 150g Heavy Cream and 5g Lemon Juice, and mix until uniform. **Key Tip:** Adding lemon juice and heavy cream simultaneously can cause separation due to the acid. Add them after mixing in the cake flour.
    🕒 04:48
16. Pour the finished cheesecake batter over the brownie batter in the pan as the second layer.
    🕒 05:09
17. Begin baking in a preheated oven at 210°C (410°F).
    🕒 05:17
18. Reduce the oven temperature to 200°C (390°F) and bake for 30 minutes.
    🕒 05:20
19. The cake is done when it still has a slight jiggle.
    🕒 05:25
20. After the cake has cooled slightly, it's essential to chill it thoroughly in the refrigerator. **Key Tip:** The chilling time greatly affects the texture. Chilling overnight or longer results in a richer flavor, allowing you to enjoy it at your preferred consistency.
    🕒 06:24