1Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets. Sift together the flour, baking soda and salt, set aside.
2Sift together the flour, baking soda, and salt. Set aside. In the microwave or over a double boiler, melt chocolate stirring frequently until smooth. Remove from heat.
3In a medium bowl, cream together the shortening, butter, and brown sugar. Beat in the eggs, one at a time, then stir in the vanilla and melted chocolate. Mix in the dry ingredients alternately with the sour milk. Drop dough by rounded teaspoonfuls onto the prepared cookie sheets about 2 inches apart.
4Bake for 8 to 10 minutes in the preheated oven, until firm to the touch. Remove from baking sheets to cool on wire racks.