Preheat oven to 350°F and position your baking rack in the middle of the oven.

In a stand mixer cream the butter and sugar together for 2-3 minutes on high until light and fluffy (important don't skimp on the time here).

Add in the egg until fully combined.

In a small bowl whisk together the flour, baking soda and salt. In a measuring cup add your buttermilk and stir in the vanilla.

To the stand mixer alternate the flour and buttermilk mixture starting with the flour first until all combined (I do about a third of the flour, then half the buttermilk, then ⅓ of the flour, then the rest of the buttermilk, then the rest of the flour).

Place parchment paper on a cookie sheet and scoop ¼ cups of batter for each cookie. You will want to leave 2 inches of space between each cookie.

Bake for 15-17 minutes or until the tops are golden brown and puffed up in the center. When you touch the center of the cookie,it should spring back like a cake. When this happens, you know they are done.

Cool on your cookie sheet completely. You will want the cookies to be fully cooled, so icing does not melt. It took about 40 minutes for mine to cool.

Add the powdered sugar, corn syrup, lemon juice, vanilla, and 1 tablespoon water in a small bowl until smooth.

Put half the icing into a second bowl and add in the cocoa powder. Add about 3-4 tablespoons of water to cocoa mixture until it is the same consistency as the vanilla icing.

You will want to ice the flat side of the cookie first.

I put the vanilla frosting on first, then waited about 5 minutes for vanilla frosting to set before spreading chocolate frosting on the other side.