I am baking the Peanut Butter Cheesecake. The recipe says to press the biscuit base up the sides of the tin, but the picture does not show that. Which is correct? And I assume the peanut butter is the processed, supermarket style with salt and sugar added?
Nigella's Chocolate Peanut Butter Cheesecake (from KITCHEN) has a biscuit crumb base made from digestive biscuits, peanuts, chocolate chips and butter. The base is pressed mostly into the base of the springform tin but Nigella suggests pressing some up the sides of the tin, to help to reduce the risk of the cheesecake batter flowing out of the tin at the base. However you do not need to put the crumbs completely up the sides of the base, just a small lip about 1cm (1/2 inch) up the side. But if you prefer to just press the crumb mixture into the base of the tin then that will work too.
The peanut butter should be a regular smooth (creamy) peanut butter as this has a softer texture and some added sugar that is needed to make a sweet and velvety cheesecake filling. Natural peanut butters tend to be a bit firmer, can be grainier and will not usually blend quite as smoothly with the eggs and cream cheese.