Step 2

Turn the oven up to 240°C / 475°F / fan 200°C. Using the paddle attachment, beat the cream cheese on medium-low until creamy, about 2 minutes. With the mixer on low, add the sugar in a steady stream, then the flour and a pinch of salt, scraping down the bowl and the paddle twice.

Step 3

Swap to the whisk attachment. Add the vanilla, lemon zest and lemon juice. Whisk in the eggs and the extra yolk one at a time, scraping the bowl well between each. Still on low, pour in 200ml of the sour cream and whisk just until blended — the batter should be smooth, light and a little airy, so don't over-beat. Keep the remaining sour cream for the topping.

Step 4

Brush the sides of the tin with a little melted butter and set it on a baking sheet. Pour in the filling and smooth the top, sinking any lumps with the tip of a knife. Bake for 10 minutes at 240°C, then turn the oven down to 110°C / 225°F / fan 90°C and bake for 25 minutes more. Shake the tin gently — the filling should have a slight wobble in the centre.

Step 5

Turn off the oven. For a creamy centre, open the door; for a firmer texture, leave it closed. Cool in the oven for 2 hours.

Step 6

Run a knife around the sides of the tin, unlock and carefully slide the cheesecake onto a serving plate.

Step 7

Stir the reserved sour cream together with the extra 150ml sour cream, 1 tbsp sugar and 2 tsp lemon juice. Spread over the cooled cheesecake right to the edges. Cover loosely with foil and refrigerate for at least 8 hours, or overnight.