Almond Croissants

Preparation - Preheat the oven to 350°F. Position a rack in the center of the oven and preheat the oven. Line a baking sheet with a silicone baking mat or parchment paper.

Simple Syrup - To make the simple syrup, add the granulated sugar, water, and rum to a small saucepan. Set over medium heat and cook, swirling the pan occasionally, until the sugar completely dissolves, 1 to 2 minutes. Set aside to cool while preparing the frangipane.

Frangipane - To make the frangipane, whisk together the almond flour, all-purpose flour, and salt in a medium mixing bowl. Use the whisk to break up any large clumps in the almond flour.

Frangipane - In a large mixing bowl, combine the softened butter and powdered sugar with a rubber spatula until smooth.

Frangipane - Add the egg and almond extract to the butter mixture and stir until fully incorporated. The mixture will break and separate at first, but keep stirring and it will come back together into a smooth batter. Fold in the almond flour mixture with a rubber spatula until fully combined and smooth.

Assembly - Slice the croissants in half horizontally with a serrated bread knife. Brush the cut side of each half generously with the simple syrup, or give them a quick dip, cut side down. Use up all of the syrup.

Assembly - To assemble, use 2/3 of the frangipane to spread an equal amount on the bottom half of each croissant, about 2 1/2 tablespoons per croissant. Replace the tops, sandwiching the filling. Use the remaining 1/3 of the frangipane to spread over the top of each croissant, about 1 1/2 tablespoons per croissant. Sprinkle a small handful of the sliced almonds on the top of each croissant, gently pressing them in so they stick to the frangipane.

Baking - Bake the croissants in the preheated oven for 20 minutes, or until the almonds have started to toast and the frangipane on top starts to brown at the edges. Serve warm or at room temperature.