Start by pre-heating your oven to 190c/375f. Also slice your croissant in half and place this on a baking paper lined tray.
Add the sugar and water into a small bowl. Stir this then put it in the microwave for 15 seconds.
Take this out and stir, then put if back in the microwave for another 15 seconds. Keep repeating this until the sugar has completely dissolved.
Leave this aside.
Melt your butter, then mix this with the icing sugar.
Add the ground almonds, flour and vanilla into this. Mix until a paste forms.
With a pastry brush, coat the cut sides of the croissant with the simple syrup.
Spread a thin layer of the almond filling onto the bottom half of the croissant. Add the top half of the croissant onto this.
With the left over filling, spread this on the top of the croissant. Then add your almond slices onto this, press them into the filling so that they stick.
Bake for around 10-15 minutes, or just until golden brown and crispy on top.
Once done, leave to cool down for a few minutes, dust with some icing sugar and then enjoy!
