1. Heat oven to 350°F.
2. Beat butter, granulated sugar and brown sugar in large bowl until light and fluffy; blend in eggs and vanilla. Stir together flour, cocoa, baking soda and salt; gradually add to butter mixture, mixing well. Stir in oats and nuts. (Batter will be stiff.) Drop by rounded tablespoonfuls onto ungreased cookie sheet.
3. Bake 11 to 12 minutes or until set; cookies will be slightly moist in center. Do not overbake. Cool 1 minute; remove from cookie sheet to wire rack. Cool completely. Makes about 48 cookies.