1. To make the filo shards, melt the butter and prepare the sugar in a bowl. Preheat the oven to 180C/350F/gas 4. Line a large baking sheet with parchment.
2. Working quickly so the pastry doesn’t dry out, spread the first sheet on a board, brush with butter and sprinkle with sugar. Layer with the next sheet and press it on with your palms. Brush with butter, sprinkle with sugar and continue in the same way with the remaining sheets. Make sure you have some butter and sugar left for the top layer. Cut the stacked sheets in half for the ease of handling and transfer onto the baking sheet. Bake for about 10 minutes, until golden, crunchy and puffed up in places. Cool on a wire rack and store in an airtight box until needed.
3. For the strawberry version, hull the strawberries and reserve about 8 nicest berries. Slice the rest of them thinly, toss with the icing sugar and lemon zest, and leave to macerate for at least an hour.
4. For the blueberry version, preheat the oven to 230C/450F/gas 8. Roasted blueberries can be made well in advance; they’ll keep in the fridge for a week and can be used in all kinds of other dishes and desserts.
5. Spread half the blueberries in a shallow oven dish and sprinkle with the teaspoon of sugar. Bake them for 10 minutes, shaking the dish so they roll about, halfway through the time. Remove from the oven, drizzle with a little lemon juice and leave to cool.
6. Whip the cream with the sugar and vanilla extract.
7. To assemble the mess, place a generous couple of spoonfuls of the macerated strawberries/roasted blueberries at the bottom of the serving bowls or cups.
Break the filo pastry into rough shards (it will be messy!) and stir into the whipped cream, one portion at a time. Scoop it with two spoons and place in the bowls. Add more shards or cream, as desired.
8. Top with the fresh berries and serve immediately.