To make the biscuit base, place the cookies, icing sugar and butter in a food processor and process for 1 minute or until the mixture is finely chopped and sticks together.

Using the back of a spoon, firmly press the mixture into a lightly greased 10cm x 20cm loaf pan lined with non-stick baking paper, and place in the freezer for 30 minutes.

While the base is setting, place half the raspberries, half the icing sugar and vanilla powder in a bowl and crush with a fork to form a purée. Set aside.

Place the yogurt and remaining icing sugar in a bowl of an stand mixer and beat until just combined. Pour the mixture into your chilled ice cream maker and churn until creamy and thick. Add half the raspberry pureé just at the end of churning, to create a ripple effect. 

Remove the base from the freezer and transfer the yogurt ice cream to the prepared tin. Spread evenly and swirl through the remaining raspberry purée. Top with the rest of the frozen raspberries. 

Cover securely and freeze for 3-4 hours or until firm. Cut into bars and serve immediately. Makes 8 servings.