Bring water and sugar to a boil until sugar is dissolved. Remove from heat and stir in vanilla and rum extract. Let cool.
1 cup water, 1/4 cup granulated sugar, 1 teaspoon vanilla extract, 1/2 teaspoon rum extract
Combine almond flour, butter, sugar, eggs, almond extract, all-purpose flour and salt in a bowl. Mix well.
1 cup almond flour, 1/2 cup salted butter, 1/2 cup brown sugar, 2 large eggs, 1/2 teapsoon almond extract, 1/8 teaspoon salt, 2 Tablespoons all-purpose flour
Split croissants in half. Brush or dip with syrup. Spread about 2 Tablespoons filling inside and 1 Tablespoon on top. Sprinkle with sliced almonds.
8 day-old or stale croissants, 1/4 cup sliced almonds, Powdered sugar
Bake for 14-18 minutes at 350°F.