Cream together the sugar, salt, butter, vanilla and egg. Sift together the flour, baking soda and cocoa. Add this to the first mixture alternately with the buttermilk. Drop the batter by teaspoonfuls (40 batter drops for 20 snack cakes) onto a greased cookie sheet and bake the cookies at 400 degrees for 7-8 minutes. Set the cakes aside to cool.
As soon as the cakes are cool, put the sandwiches together by spreading or piping buttercream on one cake, then placing another cake on top to make a sandwich. Shake sprinkles around the edges of the buttercream and top with powdered sugar, if desired.
Store in an airtight container, or wrap each cake in plastic wrap individually.
Notes
The number of servings will depend on how big you make your cakes. We usually end up with about 20 sandwiches that are about 2 inches in diameter.