• Preheat the oven to 350 degrees F. Stir together buttermilk and vanilla then set aside.
• Add the butter and sugar the bowl of your electric mixer and beat on medium-high speed until light and fluffy, about 5 minutes. Add the eggs and beat for another 2 to 3 minutes until combined, scraping down the sides if needed. In a small bowl, combine the flour, baking soda and salt. With the mixer on low speed, add half of the dry ingredients to the bowl. Pour in the vanilla buttermilk. Once combined, add the remaining dry ingredients.
• Use a tablespoon measure to scoop out 2 tablespoons of batter and place them about 2 inches apart on a baking sheet. I took the back of a spoon and spread the batter out a bit until it formed a circle. Bake the cookies for 12 to 13 minutes, or until they are slightly golden around the edges. I let the cookies cool for a few minutes on the sheet them removed them with a spatula and placed them on a cooling rack to cool completely. Once the cookies are completely cool, I take a butter knife or spoon and gently scrape off all the remaining crumbs on the flat side of the cookie.

icing

• Add the powdered sugar to a large bowl. Add in the corn syrup, lemon juice, vanilla extract and 1 tablespoon water, whisking and stirring until all the sugar lumps dissolve and a white glaze forms. If the glaze is still a bit thick, add an additional tablespoon of water. You want the icing spreadable but not liquidy.
• Transfer half of the icing to another bowl and whisk in the cocoa powder. Add the remaining 2 tablespoons of water and stir and whisk until a dark chocolate glaze forms – the same consistency of the white one. To frost the cookies, I like to start with the white glaze and use a spoon, drizzling a line down the center. I then use the back of the spoon to frost the remaining cookie. I frost all the white halves first, then do the black. I then let the cookies set for an hour or two so the glaze sets. You can pop them in the fridge or freezer before adding ice cream and the glaze will hold up a bit more.
• I suggest serving these as an ice cream sandwich “bar” – by having people scoop their own ice cream in between the cookies and pressing them together. You can make a few ahead of time and store them in the freezer for quick grabbing, but one size of the black and white frosting will get a little gooey and stick to the tray or plate they are set on.