Prepare the dry mixture. In a small bowl, thoroughly combine the all-purpose flour with the baking powder. Set the mixture aside while preparing the remaining ingredients.

Mix the butter and wet ingredients. Using an electric mixer, beat the cooled melted butter until light and fluffy. Add the eggs, granulated sugar, and almond extract, then continue mixing until thoroughly incorporated. The mixture may have a somewhat chunky appearance at this point.

Form and chill the dough. Gradually incorporate the flour and baking powder mixture into the butter mixture. Mix only until everything is combined, taking care not to overwork the dough. Refrigerate the finished dough for at least 1 hour so that it becomes easier to handle.

Shape and bake the cookies. Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper. Using a small cookie scoop or tablespoon, portion the chilled dough and roll it into balls. The dough will remain fairly sticky. Arrange the dough balls approximately 1 inch apart on the prepared baking sheet.

Bake for 8–10 minutes, or just until the cookies are set. Avoid baking them for too long, as this can cause them to become dry. Transfer the cookies to cool completely before applying the icing.

Make the almond icing. Place the sifted powdered sugar in a bowl. Add the milk 1 tablespoon at a time, stirring after each addition until a thick glaze develops. Mix in the almond extract until evenly distributed.

Glaze and decorate. Position a cooling rack inside a baking sheet so the pan can collect any dripping icing. Once the cookies are completely cool, hold each cookie upside down and dip the top into the prepared glaze.

Turn each glazed cookie upright and place it on the cooling rack, allowing the excess icing to drip onto the baking sheet below. Immediately scatter nonpareil sprinkles over the wet glaze before the icing begins to set.