Start by slicing your croissant horizontally like a sandwich. Make sure not to cut all the way through so it stays connected. This helps hold the filling inside and keeps the structure intact. A slightly stale croissant works best for this step.
In a bowl, mix butter and sugar until creamy and smooth. Add the egg, almond flour, flour, milk, and extracts, then mix until fully combined. The texture should be thick yet spreadable, similar to a soft paste.
Spread a generous layer of almond filling inside the croissant. Close it gently and spread more filling on top. Don’t be shy here—the filling is what makes it rich and delicious.
Sprinkle sliced almonds evenly over the top layer of filling. Press them lightly so they stick while baking. This step gives your croissant that classic bakery look and crunch.
Place the croissant on a lined baking tray and bake in a preheated oven at 180°C (350°F). Bake for about 15–20 minutes until golden brown and crisp. The filling should be slightly puffed and set.
Let the croissant cool for a few minutes after baking. Dust lightly with powdered sugar for a beautiful finish. Serve warm for the best taste and texture.