1. Combine the crushed digestive biscuits with the melted butter and press into a tin. Chill in the fridge while you make the topping.
2. Pour the double cream into a bowl, add the cream cheese and Nutella.
3. Whisk until it's very thick – almost the consistency of ice cream. Use an electric whisk if you have one.
4. Remove the base from the fridge and add the cheesecake mixture, smoothing the top.
5. Pop into the fridge for at least 4 hours (or overnight is much better if you don't need it until the next day).
6. When the cheesecake is well chilled, warm the Nutella very gently in a pan on the hob or in the microwave. (Don't let it get hot, it just needs to soften very slightly.)
7. Remove the cheesecake from the fridge and, while still in the tin, pour the melted Nutella over the top. Smooth it out very gently with the back of a spoon, until the top is completely covered. (Take care not to touch the cheesecake mixture.)

Return the cheesecake to the fridge for at least a further 30-60mins