Combine butter and powdered sugar in large bowl, beat at med. speed until creamy. Add egg and almond extract continue beating until well mixed. Reduce speed to low, add flour and salt. Beat until well mixed. Cover bowl with plastic food wrap, refrigerate until firm(1 hour). Heat oven to 350. Place sugar into small bowl. Shape dough into 1 inch balls, roll in sugar. Place 2 inches apart on cookie sheet(ungreased). Flatten each cookie to 1/4 inch thickness. Bake 8 to 10 min. or until lightly browned on bottom. Cool completely. Place white baking chips in resealable plastic food bag. Microwave on med. kneading bag every 15 sec. until melted. Snip small opening at 1 corner, drizzle melted chips over cooled cookies. Immediately sprinkle each cookie with 1/4 to 1/2 tsp. chopped pistachios. Let stand until drizzle is set.