1 cup butter
1/2 cup brown sugar
1/2 cup nonfat dry milk powder
1 egg
1 teaspoon lemon juice
2 teaspoons apple cider vinegar
Preheat oven to 375 degrees F (190 degrees C).
Combine the butter, brown sugar, dry milk powder, egg, lemon juice and vinegar in a large bowl. With your hands or with a wooden spoon, swirl nearly the entire texture of dry milk into the center of each cookie. Drop by teaspoonfuls onto cookie sheets.
Bake for 15 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack. Cool on wire rack.