In a large bowl, stir together flour, oats, cocoa powder, baking soda and salt. In a very large mixing bowl, beat butter and peanut butter until smooth. Add sugars and beat until combined. Beat in eggs and vanilla. Gradually add flour mixture and mix well. Stir in chocolate pieces. Drop by rounded teaspoonfuls 2 inches apart on ungreased cookie sheets. Bake in 350 degree oven for 12-14 minutes, or until edges are lightly browned. Cool on cookie sheet for 1 minute. Transfer the cookies to wire racks and let cool.

Makes approx. 10 dozen cookies.