Combine milk and cream in medium saucepan. Whisk in combined sugar, dextrose, and milk powders. Cook on medium heat, stirring occasionally, until mixture reaches 165°F. Remove from heat. Stir in 2 oz. cookie pieces; let stand 10 min.
Pour small amount of mixture into blender and process 30 seconds. Transfer to clean bowl and chill over an ice bath. Continue until all of mixture has been processed. Stir in vanilla. Refrigerate overnight.
Freeze mixture in ice cream maker according to manufacturer's directions. Spoon prepared ice cream into freezer container. Gently fold in remaining cookie pieces. Freeze until firm.
For each serving, use #30 scoop to portion 3 scoops (5.5 oz.) ice cream into serving dish.