1 1/2 pounds full-fat cream cheese
1 teaspoon vanilla extract
4 ounces (1/2 cup plus 1 tablespoon) caster sugar
3 large eggs
3 ounces mixed berries
Line the base of a spring form pan with parchment paper. Place the biscuits in a food processor and whiz into fine crumbs using the blade attachment. Tip the crumbs into a bowl, add the melted butter, and mix together with a spoon. Place the mixture in the prepared tin, pressing it into the base with the back of the spoon. Place in the refrigerator and allow to cool and set for 20-30 minutes.
Preheat the oven to 320°F. Using an electric mixer, mix together the cream cheese, vanilla extract, and sugar on medium speed until smooth. Break the eggs in one at a time, mixing thoroughly after each addition and scraping down the sides of the bowl to make sure every bit is incorporated. Stir in the mixed fruits by hand, checking that they are evenly dispersed, then pour the mixture into the prepared tin.
Create a water bath for the cheesecake. Wrap the outside of the spring form with foil, folding it up around the sides of the pan. Then place thepan in a roasting tin and fill with water to about 1/4 inches below the top edge. The moisture created in the oven helps to prevent the top of the cheesecake from cracking. Run a palate knife around the inside edge of the pan; this releases the mixture from the sides so that it doesn't stick.
Place in the oven and bake for 35-45 minutes, or until the cheesecake is a light-golden color on top (more so around the edges) and generally firm to the touch, with only a slight wobble in the middle.
Keeping the cheesecake in the tin, allow it to cool down at room temperature, then place in the fridge to set for a few hours, or preferably overnight. Once the cheesecake has set, it can be taken out of the pan and decorated with extra berries or whipped cream.