In a large bowl cream butter with both sugars until light and fluffy using an electric mixer on medium speed. Blend in egg and vanilla. In a medium bowl whisk together flour, cocoa powder, baking soda and salt until combined.
Add the flour to the butter mixture alternately with the milk, beating till smooth. Drop the dough by tablespoonfuls’ onto the prepared baking sheets spacing 2 inches apart. Bake 15-16 minutes or until tops of cakes spring back when touched. Allow to slightly cool in pan for 2 minutes and move to cooling rack to continue to cool completely.
In a medium bowl combine goat cheese, cream cheese and mix well. Mix in powdered sugar until smooth. Spread on the bottoms of half of the cookies; top with crushed peppermint and remaining cookies. Sift remaining powdered sugar over tops of filled pies.