Preheat oven to 180℃ or 165 ℃ Fan forced.
In a mixing bowl add almond flour, salt and caster sugar. Mix until combined.
Add butter and using electric beater mix until it becomes crumbly.
While mixing add vanilla essence and egg, keep mixing until its smooth and creamy.
Prepare Sugar syrup by mixing raw sugar or white sugar with hot water. Mix until sugar dissolves.
Slice each croissant in half horizontally. Lightly brush the inside of the bottom half with the sugar syrup.
Spread a generous layer of almond filling on the bottom half, then place the top half back on.
Brush the top with sugar syrup as well and spread a thin layer of almond cream over it. Sprinkle flaked almonds over the top and place the croissants on a lined baking tray.
Bake in a preheated oven at 180°C (350°F) for 15–20 minutes, or until golden and crisp.
Allow the croissants to cool slightly, then dust with icing sugar before serving.