Preheat the oven to 170C/325F/Gas 3. Line a 12-hole muffin pan with muffin cases, and set aside.

Stir together the biscuit crumbs and sugar. Add the melted butter and mix until all the crumbs are moist.

Divide the mixture between the muffin cases and press firmly into an even layer.

Bake for 7 - 8 minutes, then allow to cool whilst preparing the cheesecake.

In a large mixing bowl, whisk together the cream cheese, sugar, egg, egg yolk, vanilla, and yogurt until combined.

Divide the mixture between the prepared muffin cases.

Add the raspberries to a food processor or blender, and pulse until pureed.

Press through a fine mesh strainer into a small bowl to remove seeds and pulp.

Dollop small amounts of the raspberry sauce on top of the cheesecakes, and use a toothpick to create swirls.

Bake for 20 - 25 minutes or until slightly puffed up and just set.

Allow to cool completely in the pan on a wire rack, then refrigerate for 2 - 4 hours.