Cup of Yum
1. Leave the croissants out on the counter uncovered overnight to help dry them out.
2. The day after, preheat the oven to 350°F and line a baking sheet with parchment paper.

Simple syrup

1. Add the water and sugar to a small saucepan and bring to a simmer. Simmer until all the sugar has dissolved.
2. Remove from the heat and stir in almond extract. Let cool completely.

Almond filling

1. In a large bowl, whisk together the almond meal or flour, sugar, and salt.
2. Add the butter and almond extract and beat until fully combined.
3. Add the eggs one at a time and then beat on high until you achieve a fluffy and creamy frosting consistency.

Assembly and Baking

1. Slice open the stale croissants. Use a pastry brush to generously brush the simple syrup over the insides of the croissants.
2. Spread a layer of almond filling on the bottom half of each croissant, about 2-3 tablespoons. Top with the top half of the croissant.
3. Once all the croissants are filled, mix the remaining almond filling with 2 tablespoon of milk to thin. Spread it evenly over the top of the croissants. Sprinkle with sliced almonds. You can use your hand to press the almonds into the almond filling to prevent them from falling off while baking.
4. Bake for 13-15 minutes, until the almond filling on top begins to turn golden brown and the sliced almonds are getting toasted.
5. Let cool before dusting with powdered sugar. These croissants are best served the same day they are made.