When you’re ready to bake, heat the oven to 170°C/150°C fan/gas mark 3. To make the filling, beat the cream cheese and sugar in a bowl, using an electric mixer, until soft and well combined. Add the soured cream and beat on a slow speed to combine. Don’t overbeat the mixture or beat it too fast, as this will beat in air and make the cheesecake rise as it cooks, then crack as it cools – always set the mixer speed to slow-medium. Add the eggs one at a time, beating in each one until incorporated. Add the lemon zest and juice, then beat slowly for about a minute.