1. To make the crystallised lavender, start with a sugar syrup by putting the caster sugar and water in a pan and bring to the boil, allow it to reduce by half, then add the dried lavender and simmer for 2 minutes. Drain it in a sieve.
2. Spread the lavender on a baking sheet and sprinkle over the granulated sugar. Bake at 70°C for two hours, until dried out.
3. Allow it to cool and then blitz it in a grinder or grind it in a pestle & mortar to a fine powder and set aside until needed.
4. Preheat the oven to 200°C.
5. Roll out the pastry until it is just smaller than the baking sheet and about 4mm thick. Prick it all over with a fork, and then place it onto a lined baking sheet. Top it with a second piece of baking paper and then another baking sheet. This is to stop the pastry puffing up too much; you want the flakiness but not the volume.
6. Bake it for 25-30 minutes, or until a deep golden colour; 10 minutes before the end, take it out and dust it with icing sugar. As soon as the pastry comes out, cut out 10 discs with the cookie cutter. Allow these to cool completely.
7. Repeat with the remaining half of the pastry (if you have enough baking sheets you can do this all in one batch).
8. To make the cream filling, simply whip the double cream to peaks that are just a little firmer than soft and floppy. Fold in the mascarpone, vanilla, framboise, icing sugar and a small pinch (about ¼ teaspoon) of the crystallised lavender and refrigerate the filling until needed.
9. To assemble them, take 10 of the pastry discs and place them on a flat serving plate or tray. Fill a piping bag with the filling and pipe a small ball of filling into the centre of each disc. Dot 4-5 raspberries around the filling, touching the cream to help fix them in place.
10. Pipe more filling between the raspberries. Then top with another disc of puff pastry. You should have 10 perfect millefeuille.
11. Top each one with a small sprig of lavender flowers and a heavy dusting of icing sugar.