4 ounces almond paste (about 5 1/2 tablespoons)
1/2 cup confectioners sugar, plus more for dusting
Pinch of fine salt
1 large egg white
1/4 teaspoon pure vanilla extract
1/4 cup sliced almonds
Preheat the oven to 300F. Line a baking sheet with parchment paper, and set aside. Place the almond paste, sugar, and salt in the bowl of an electric mixer fitted with the paddle attachment; beat on medium speed until the mixture looks crumbly, about 3 minutes. Add the egg white and vanilla. Continue beating until the mixture is smooth and thick, about 3 minutes more. Drop 12 even tablespoons of batter about 2 inches apart on the lined baking sheet; place 2 almond slices on each mound of dough. Bake the cookies, rotating the baking sheet halfway through, until golden brown, 20 to 25 minutes. Transfer the cookies to a wire rack; let cool completely. Just before serving, lightly dust with confectioners sugar.