Giant Almond Croissant

Name: Giant Almond Croissant
Ingredients: 1 sheet store-bought puff pastry (any size), thawed (see Tip); 1/2 cup/100 grams granulated sugar; 4 tablespoons/56 grams unsalted butter, melted; 1 teaspoon kosher salt (such as Diamond Crystal) or 1/2 teaspoon coarse kosher salt (such as Morton’s); 3/4 cup/108 grams blanched almond flour (see Tip); 1 large egg; 1 tablespoon dark rum or 1 teaspoon pure vanilla extract; 1 1/2 teaspoons almond extract; 1/2 cup/45 grams sliced almonds; Flaky salt, for topping; Confectioners’ sugar, for serving