To make the cookies:
Preheat oven to 350°F.
Whisk together flour, baking soda, and salt in a bowl. Stir together buttermilk and vanilla in a cup.
Beat together butter and sugar in a large bowl with an electric mixer until pale and fluffy, about 3 minutes. Then add the eggs, beating until well combined. Mix in flour mixture and buttermilk mixture alternately in batches at low speed (scraping down side of bowl occasionally), beginning and ending with flour mixture. Mix until smooth.
Spoon 1/4 cups of batter about 2 inches apart onto a buttered large baking sheet. Bake in middle of oven until tops are puffed and pale golden, and cookies spring back when touched, 15 to 17 minutes. Transfer with a metal spatula to a rack and chill (to cool quickly), about 5 minutes.
To make the glazes:
In a bowl, whisk together the powdered sugar, 1/2 teaspoon vanilla extract, 1 tablespoon of corn syrup and 2 tablespoons hot water, until smooth. That’s your vanilla glaze.
In a separate bowl, melt the butter and the chocolate in a microwave for about 1 minute. Add the corn syrup and stir until smooth. That’s your chocolate glaze.
Once the cookies are cooled, face them all bottom side up of a clean surface. Spread half of the cookie with vanilla glaze and the other half with chocolate glaze. Refrigerate for 20 minutes to set.
by The Savvy Kitchen