Preheat oven to 350 degrees F.

Whisk together flour, cocoa powder, salt and baking soda in a medium sized bowl.

Pour vinegar into a measuring cup. Add milk to fill to the one cup mark. Set aside for five minutes to allow vinegar to sour milk. Stir in vanilla.

In a large bowl, cream butter and brown sugar until light and fluffy.

Add egg and mix well to combine.

Add 1/3 of flour mixture to butter/brown sugar and mix until just combined.

Add 1/2 of liquid to butter/brown sugar and mix until just combined. Continue by adding 1/3 flour and mixing, adding the remaining liquid and mixing and finally adding the rest of the flour and mixing. Do not over mix.

Drop by tablespoonful onto parchment paper-lined cookie sheets. You should be able to fit 12 on a cookie sheet.

Bake for 11-12 minutes, or until tops spring back when pressed lightly. Cool on wire rack. Repeat with remaining batter.

Cream butter and icing sugar together until well mixed.

In a separate dish stir together milk, peppermint extract and vanilla extract. Add to icing sugar and mix well.

Fold in crushed candy canes. (I crushed mine in bag using a rolling pin but you could use a jar or whatever you have handy.)

Spread a spoonful of icing on a chocolate cake and top with a similar shaped cake.