Preheat oven to 350 degrees. In a large bowl combine the butter and sugar and beat until light and fluffy. Add the eggs and vanilla and beat until well combined. Stir together flour, cocoa, baking soda, salt; add to the bowl with the wet ingredients.
Drop dough by rounded teaspoons onto a parchment lined cookie sheet. Bake for about 10 minutes or just until set. (Cookies may appear soft but will set up after removing them from the oven to cool for a few minutes.) Place a peppermint kiss in the center of each cookie.