Cream butter, shortening and sugars until fluffy. Add eggs and
vanilla and mix well.
Combine flour, soda, salt, add to butter mixture and combine, add
chocolate chips.
Drop with cookie dropper onto ungreased cookie sheets.
Bake at 350F for about 10-12 minutes. Wait just a minute or two and
place on wire rack. Don't brown, just bake until set and edges
starting to turn light brown.