1In large bowl, beat 1 cup of the butter, 1/2 cup of the powdered sugar and the salt with electric mixer on medium speed about2 minutes or until creamy. Beat in 1/4 teaspoon of the almond extract. On low speed, beat in flour just until combined. Cover; refrigerate 30 minutes.
2Heat oven to 350°F. Line cookie sheets with cooking parchment paper. Shape dough into 48 (3/4-inch) balls. Roll 16 balls in each color of sanding sugar, coating completely. On cookie sheets, place balls 1 inch apart.
3Bake 15 minutes or until set and bottoms are light golden brown. Remove from cookie sheets to cooling racks. Cool completely, about 30 minutes. In small bowl, beat remaining 1/4 cup butter, 1 cup powdered sugar, 1/4 teaspoon almond extract and the milk with electric mixer on medium speed until smooth. For each sandwich cookie, spread about 1/2 teaspoon filling on bottom of 1 cookie; top with second cookie, bottom side down, to form ball.