Make the simple syrup: Place water and sugar in a saucepan and bring to a simmer. Stir until sugar is fully dissolved, then remove from heat and add almond extract. Set aside and allow to cool.

Blanch almonds: Place enough water to cover your almonds in a saucepan and bring to a boil. Once boiling, add almonds to pan and boil for one minute. Immediately remove from heat and run under cold water. Now you will be able to easily remove the almond skin. Simply pinch the almond between your fingers and the skin should slide right off. Be sure to aim into a bowl as these have a tendency to fly across the room!

Preheat oven to 350°. In the bowl of your food processor, pulse almonds until finely ground. Add sugar and a pinch of salt, pulse until combined. Add butter and pulse until combined. Add the egg and extract, and process until creamy and fluffy (a few minutes).

Slice croissants in half. Dip each half into the simple syrup just until fully covered. Do not soak them. Place bottom half on a parchment lined baking sheet. Spoon 2 tablespoons of filling, spreading evenly over the croissant. Top with other half. Repeat with remaining croissants. Use the remaining filling to spread over the top of each croissant. Sprinkle with sliced almonds.

Place in preheated oven and bake for 15 minutes, or until the top becomes golden brown. Remove from oven and sprinkle with powdered sugar.

Make sure to set aside enough time to let these cool before serving. They’re one of the few things that aren’t best served fresh out of the oven.