Cream butter and sugar together until light and fluffy, and then beat in egg and vanilla. On top sift cocoa powder, flour, salt, and baking soda. Beat until just combined.
Place parchment paper or wax paper on cookie sheets, and using a cookie scoop, make 20 cookies. Roll them into sprinkles and place on cookie sheet. Bake for 7-8 minutes until just firm. As soon as you pull them out place a kiss in the middle of each one, and transfer to a cooling rack.
Notes
*You can use all types of sprinkles or roll them in sugar, drizzle them with chocolate, or dust them with powdered sugar after baking