Blueberry Cheesecake

Step 1: Heat the oven to 160°C/320°F (140°C fan) and place a shelf in the middle of the oven.

Step 2: Use a 20 cm/8-inch springform cake tin. Turn the base upside down, butter it lightly and press a square of parchment paper onto it. Clip the base into the springform pan, leaving the excess paper sticking out.

Step 3: Butter and line the sides of the pan.

Step 4: Break the biscuits up roughly by hand and put them in a food processor.

Step 5: Process the biscuits into fine crumbs. Add the butter and briefly process until it is dispersed and the mixture resembles wet sand.

Step 6: Pour the crumb mixture into the prepared tin. Use a spatula to spread it roughly over the base and up the sides.

Step 7: Use an object with a flat base and straight sides, such as a measuring cup, to press the crumbs up the pan sides almost to the top. Flatten the base as well.

Step 8: Using a stand mixer fitted with a paddle or a handheld beater, beat the cream cheese just until smooth, no longer than 20 seconds at speed 4. Avoid adding too much air to the filling, as that can cause cracks during baking.

Step 9: Add the flour and beat for 5 seconds at speed 4, just until incorporated.

Step 10: Add the vanilla, sour cream, sugar and lemon zest. Beat just until combined, no more than 10 seconds at speed 4.

Step 11: Add the eggs one at a time, beating for 5 seconds at speed 4 between each addition. After the last egg, beat only as needed to make the batter smooth; stop as soon as it is smooth.

Step 12: Fold in the blueberries with a rubber spatula. Pour the filling into the prepared crust.

Step 13: Bake for 70 minutes. The top should be slightly puffed and very light golden brown, not cracked, and nearly flat. The cheesecake should jiggle slightly when you gently shake the pan; it will set as it cools.

Step 14: Leave the oven door open about 20 cm/8 inches and cool the cheesecake in the oven for about 2 hours. Then refrigerate it in the pan for at least 4 hours or overnight. The cake will sink and the surface should become flat.

Step 15: Remove the sides of the springform pan. Use the overhanging parchment paper to slide the cheesecake off the pan base, then slide the cheesecake off the paper.

Step 16: Put 1 cup of the blueberries (125 g/4 oz), the vanilla, sugar and lemon juice in a saucepan. Stir, then bring to a simmer over medium heat. Simmer for 7 minutes, until the blueberries break down.

Step 17: Mix the cornflour or cornstarch with the water, then stir the mixture into the pan. It will thicken quickly.

Step 18: Stir in the remaining blueberries. When the sauce is syrupy, remove it from the heat and let it cool. It will thicken as it cools.

Step 19: Once cool, stir the sauce. Adjust its thickness by adding water 1/2 teaspoon at a time until it has a gently flowing consistency. Take care not to make it runny.

Step 20: Spoon the sauce over the cheesecake until it is completely covered. There may be about 1/2 cup of sauce left for touch-ups. Refrigerate the topped cheesecake for at least 2 hours.

Step 21: Slice and serve.