Prepare the Croissants: Ensure your one-day-old croissants are dried out by simply storing them uncovered at room temperature overnight. If they're fresh, slice them horizontally and bake at 175°F for 30-40 minutes, flipping halfway until they're dry.

Create the Simple Syrup: In a saucepan over medium heat, combine 3/4 cup water, 3 tablespoons rum, and 2 tablespoons granulated sugar. Stir until the sugar melts completely, then set aside to cool.

Mix the Almond Filling: In a large bowl, blend together 1/2 cup granulated sugar, 1 cup almond flour, and 1 stick of softened butter using a hand mixer until the mixture is smooth. Add 1 egg and 1 teaspoon almond extract, blending until the filling is fluffy.

Prep the Oven: Preheat your oven to 350°F and line a baking sheet with parchment paper.

Dip the Croissants: Quickly dip each croissant in the prepared simple syrup to coat the top and bottom. Remember, don't soak them—just a light dip!

Fill the Croissants: Take the bottom half of each croissant and spread 2-3 tablespoons of the almond filling inside. Replace the tops and spread a thin layer of filling over the top for added flavor.

Add Toppings and Bake: Sprinkle about 1 tablespoon of diced almonds on each croissant, then bake for 15-20 minutes or until the tops are golden brown. Dust with powdered sugar just before serving.