Blåbær-ostekakeformkake

Fresh or frozen berries release a lot of liquid into the batter, while the jam stays thick and holds its shape as a swirl, so they are not a direct swap. If you want whole berries, toss a small handful in a little of the flour from the recipe and fold them into the cake batter, but keep the jam dollops for the marbled effect. Frozen berries should go in straight from the freezer so they do not bleed colour through the cheesecake layer.

This usually happens when the cake batter is too soft or the swirl goes too far. The batter is layered in thirds for a reason: each layer has to be firm enough to carry the cream cheese mixture, so mix it just until smooth and no longer, and spread it gently rather than pressing. The single, light pass with the wooden skewer is all the swirling the cake needs - repeated stirring blends the two mixtures into one muddy batter.

Because of the cream cheese layer this is not a cake for the countertop - wrap it well or put it in an airtight container and keep it in the fridge. Let cold slices sit at room temperature for about twenty minutes before serving, as the butter-rich crumb tastes dry straight from the fridge. The loaf also freezes well in slices, wrapped individually, and thaws overnight in the fridge.

The cheesecake mixture can be stirred together an hour or two ahead and kept covered in the fridge, then given a quick stir before layering. The cake batter, however, should go into the pan and the oven right away, since the baking powder starts working as soon as it meets the milk. If you want to bake a day ahead, the finished loaf is actually easier to slice cleanly once it has chilled.

The teaspoon of cornstarch is there to bind the cream cheese, sugar and egg so the layer sets softly instead of running into the batter. You can replace it one-to-one with potato starch, or with a teaspoon of the all-purpose flour already in your kitchen. Leaving it out entirely gives a looser, wetter layer that is more likely to blur into the cake during baking.