Preheat oven to 180° C Fan.
Place the almonds in a large frying pan and dry-fry them for 5 minutes until they are starting to brown and smell nutty. Remove from the pan and leave them to cool down.
Tip the toasted almonds alongside the pistachios in a food processor. Add the caster sugar, 2 tsp orange blossom water, cinnamon, ginger and salt. Blitz to fine crumbs. Don't worry if the nuts start looking like a rough paste, but don't process them into nut butter.
Scrape the nut mixture into a bowl. Add the room-temperature butter and mix until combined.
Unroll the filo pastry and cut the sheets into strips 6-30cm. Cover the strips with a damp towel to prevent from drying out.
One filo strip at a time, brush it with melted butter. Place a generous teaspoon of the nut mixture on the corner of the strip. and fold it over to form a triangle. Keep folding into triangles from left o right until you arrive at one folded triangle of pastry. See video below for the method.
Repeat with the rest of the pastry strips.
Brush the briouat tops with melted butter and place on a baking parchment -lined tray. Bake in the centre of the oven for 15-18 min until golden.
Whilst the pastries are baking, in a wide pan, heat the honey with the remaining tsp of orange blossom water until it is a thin syrup consistency.
When briouat are baked, transfer them to the honey syrup and soak the pastries for a minute, then turn them over and soak for another minute. Transfer them on a large plate or another baking tray to cool completely before serving.