Preheat oven to 350 degrees. Grease two cookie sheets and set aside. place the butter and sugar in a bowl and beat together until light and fluffy. Beat in the egg, then add the oats, milk and vanilla. Beat together until well lended. Sift the flour, cocoa and baking powder into the cookie batter and stir. Stir in the chocolate morsels.
Place teaspoonfuls of batter on the two cookie sheets and flatten slightly with a fork. Bake for 15 minutes, or until slightly risen and firm. Let acool on the cookie sheets for two minutes, then transfer to wire racks to cool completely.