1. Heat oven to 375°F. In a medium bowl, stir cookie mix, oil, water and egg yolk until a dough forms.
2. Shape dough into 15 (1-1/4-inch) balls and roll in sugar. Place 2 inches apart on ungreased cookie sheets.
3. Bake for 8 to 10 minutes or until light golden brown. Immediately press 1 milk chocolate candy in center of each cookie and remove from cookie sheets. Cool completely for about 20 minutes. Store cookies in tightly covered container.
For even baking, make sure cookies are the same shape and size.