Preheat oven to 350°F. In large bowl cream butter and sugars until light and fluffy; beat in sour cream, egg, maraschino cherry juice and vanilla. In medium bowl combine flour, baking soda and salt; add to creamed mixture. Stir in "M&M's"® Milk Chocolate Mini Baking Bits, walnuts and maraschino cherries. Drop by heaping tablespoonfuls about 2 inches apart onto ungreased cookie sheets. Bake about 15 minutes. Cool 1 minute on cookie sheets; cool completely on wire racks. Store in tightly covered container.