Blackberry & ricotta no-churn ice cream

Put ¾ of the blackberries in a blender or food processor with the lime juice and icing sugar; whizz until almost smooth. Cut the remaining blackberries in half. In a large bowl, use an electric hand mixer to beat the ricotta with the lime zest, vanilla and a pinch of fine salt for about 1 minute until smooth. Gradually add the condensed milk, beating constantly, until smooth. Add the whipping cream and whisk until soft peaks form (5-7 minutes).

Scatter ½ of the crushed biscuits into the bottom of a 1.5-2-litre freezerproof container (about 23cm x 15cm). Pour ½ of the cream mixture on top, followed by ½ of the puréed blackberries. Gently swirl to ripple. Sprinkle over ½ of the halved blackberries along with the remaining crushed biscuits. Pour in the remaining cream mixture, then add the remaining blackberry purée. Swirl again, then top with the remaining halved blackberries. Cover and freeze for at least 5 hours. Leave to stand at room temperature for about 10 minutes to soften slightly before serving.