Preheat oven to 350°F. Line a rimmed baking sheet with parchment paper, set aside.
Cream sugar and butter together in a large bowl. Add the egg and extract and beat until the mixture becomes thick and creamy.
Add the almond flour and all-purpose flour; mix well.
Spread approximately 2 tablespoons of the filling on the bottom half of a croissant, place the top back on, and spread another 2 tablespoons of filling on top. Sprinkle with some almonds and place the croissant on the prepared baking sheet. Repeat with remaining croissants.
Bake for 15-20 minutes, remove from oven and sprinkle powdered sugar over the croissants.
