Heat oven to 160C/140C fan/gas 3. Mix the milk powder, cornflour and half the sugar together, then pour over the melted butter and white chocolate. Mix with a spoon until it forms a crumb, then scatter over a baking sheet and bake for 10 mins until golden. Remove from the oven and leave to cool.
Remove the tops of the strawberries, then cut into quarters. Toss the strawberries in the rest of the sugar, then divide evenly between four bowls and leave to cure for 30 mins.
Add a large spoonful of cre?me frai?che to the strawberries, and scatter over the pistachios and some of the crumble (this recipe makes plenty of crumble – any leftovers will keep in a jar or airtight container for several weeks). Scatter over a few small mint leaves, if you like, to lift the flavour and colour of the dessert.