Make the syrup by boiling together the sugar and water in a saucepan until, all the sugar completely dissolves, then take off the heat and add in vanilla extract and almond paste (extract)
Whisk together the softened butter and biscoff spread (cookie butter spread) till light and fluffy
Then, add in the sugar and mix well
Now, crack in one egg and whisk to combine
Add in the vanilla, almond paste or extract, ground almonds, salt and flour and mix to fully combine
Slice open the croissants and place onto a lined baking tray, cut sides up
Brush the cut sides of the croissants generously with the syrup
Pipe or spread the biscoff almond filling evenly into the croissants and place on the croissant tops
Coat the top of the croissants with the almond syrup using a pastry brush
Pipe on some more filling and press on lots of flaked almonds
Place in a preheated oven at (180°C / 355°F / gas mark 4) and bake for 12 - 15 minutes until the croissants are golden brown
Once baked, sift on some icing sugar and drizzle on some more melted biscoff spread, optionally you can top the croissants with a biscoff biscuit as well.
Enjoy!