Preheat your oven to 350 degrees.

Make a simple syrup by placing the water and sugar in a microwave-safe bowl. Heat in the microwave for 90 seconds or until the sugar is completely dissolved. Stir in almond extract.

In a bowl, combine almond flour, softened butter, granulated sugar, egg, almond extract, and vanilla extract. Mix until well combined and smooth.

Cut each croissant in half horizontally to create a pocket for the almond filling. Lightly brush the inside of each croissant with simple syrup.

Generously spread the almond filling on the bottom half of each croissant, reserving a small amount for the top. Place the top half back on, creating a sandwich.

Spread a small amount of almond filling on the middle top of each croissant and sprinkle sliced almonds over the top, pressing them gently into the almond filling.

Place filled croissants on a parchment paper lined baking sheet and bake in the preheated oven for 12-15 minutes or until the tops are golden brown.

Allow the almond croissants to cool slightly before dusting with powdered sugar.