Japanese Cheesecake

1. Prep the oven and water bath. Heat oven to 320°F (160°C). Put a kettle or saucepan of water on to heat. Place a rack in the lower-middle of the oven.
2. Prepare the pan (leak-proof it). Grease an 8-inch springform pan and line the bottom with parchment. Optional but helpful: line the sides with a parchment collar (a strip of parchment that rises 2 to 3 inches above the rim) so the cake can climb and release cleanly. Wrap the outside of the pan with 2 to 3 layers of foil so water cannot sneak in during baking.
3. Melt the dairy base. In a medium saucepan over low heat, melt together the cream cheese, butter, and milk. Whisk until smooth and silky. Take off the heat and let it cool until warm, not hot, about 5 minutes (around 110°F to 120°F if you want to check) so the yolks do not scramble.
4. Add yolks, then sweeten it. Whisk in the egg yolks, vanilla, lemon juice, and (if using) lemon zest until smooth. Then whisk in half of the sugar (about 1/4 cup or 50 g) until dissolved.
5. Sift in the dry ingredients. Sift the flour, cornstarch, and salt into the batter. Whisk until fully combined. The batter should be smooth and pourable.
6. Whip the egg whites. In a clean, dry bowl, beat egg whites on medium speed until foamy. Add cream of tartar (if using). Gradually add the remaining sugar and beat until glossy medium peaks form. When you lift the whisk, the peak should stand and gently curl over. It should not look dry or clumpy.
7. Fold (gently, but with purpose). Stir 1/3 of the whipped whites into the yolk batter to lighten it. Then add the rest and fold with a spatula until you see no big streaks. Stop when it is combined. Overfolding deflates the batter.
8. Fill the pan. Pour batter into the prepared pan. Tap the pan lightly on the counter once or twice to pop large air bubbles.
9. Set up the water bath. Place the foil-wrapped pan into a large roasting pan. Set it on the oven rack, then carefully pour in very hot (not boiling) water until it comes about 1 inch up the sides of the cheesecake pan. Pour slowly and avoid splashing water into the batter.
10. Bake low and steady. Bake at 320°F for 25 minutes, then, without opening the oven door, reduce oven to 285°F (140°C) and bake for 45 minutes. The top should be lightly golden, the edges should look set, and the center should still wobble as one piece when you gently shake the pan.
11. Cool slowly (this matters). Turn the oven off and crack the door open about 1 inch. Let the cake sit in the oven for 15 minutes. Then carefully remove the roasting pan from the oven, lift the cheesecake pan out, and unwrap the foil only after it is out of the water bath (so you do not accidentally pour water toward the seam). Cool on a rack for another 45 to 60 minutes.
12. Unmold and chill for clean slices. Run a thin knife around the edge, release the springform, and lift off the ring. For the neatest slices, refrigerate for 2 hours before serving. If you are worried about condensation softening the top, chill the cake uncovered until cold to the touch, then wrap or cover.
13. Serve. Dust with powdered sugar if you want the classic look. Slice with a warm knife (run it under hot water, wipe dry) for pretty edges.

Tips and Variations

• If you only have all-purpose flour: Use 1/2 cup all-purpose flour spooned and leveled (about 60 g). If you scoop straight from the bag, it can land closer to 70 to 75 g, which makes the cake a little heavier.
• Prevent browning too fast: If the top is getting darker than you want, loosely lay a piece of foil over the top for the last 15 to 20 minutes.
• For extra stability: Do not skip the gradual cool-down. Sudden temperature changes are crack city.
• Matcha version: Whisk 1 to 2 tbsp matcha powder into the sifted dry ingredients.
• Orange-citrus twist: Swap lemon zest for orange zest and use 1 tbsp orange juice instead of lemon juice.
• Serving idea: Top slices with macerated berries (berries + a spoon of sugar + pinch of salt, rest 10 minutes). It is a small move that tastes like you tried very hard.