• Preheat oven to 350°F. Line two baking sheets with parchment paper.

Make the frangipane

• In the bowl of a stand mixer, or a large mixing bowl and using a hand mixer, cream together the butter and sugar until light and fluffy, about 2-3 minutes.
• Beat in the almond flour and mix for a couple of minutes, until well combined.
• Beat in the eggs until they are fully incorporated.
• Add in the all-purpose flour, almond extract and vanilla extract.

Fill the almond croissants

• Using a serrated knife, slice each croissant in half.
• Spread about 2 tablespoons of frangipane over the bottom half of each croissant. Then top with the top half.

Bake croissants

• Place croissants on the prepared baking sheets in a single layer on each sheet. Bake at 350°F for 14-17 minutes. The tops will be darker brown and crispy.

Make the syrup

• In a small saucepan over medium-high heat, bring the water and granulated sugar to a boil. Once all the sugar has dissolved, remove from the heat and stir in the vanilla extract. Allow to cool slightly until the croissants are done baking.

Top croissants

• Lightly brush the top of a croissant with the syrup. Immediately sprinkle powdered sugar on top. Then sprinkle sliced almonds. Repeat with the remaining croissants.