In large bowl cream butter and sugars until light and fluffy; beat in egg and vanilla.
In medium bowl combine flour, baking soda and salt; blend into creamed mixture.
Stir in M&M'S® & Chocolate Mini Baking Bits and nuts.
Drop by heaping tablespoonfuls about 2 inches (50mm) apart onto ungreased cookie sheets.
Bake 10 to 13 minutes or until edges are lightly browned and centers are still soft. Do not overbake. Cool 1 minute on cookie sheets; cool completely on wire racks.