These homemade Black and White Cookies are soft, sweet, and topped with half vanilla and half chocolate icing—just like the ones you'll find in New York!
Preheat oven to 350°F and combine milk and vinegar together to make buttermilk. Set aside. Then, sift flour in a mesh strainer (or a sifter if you have one) over a large mixing bowl. Measure out 1 ½ cups of sifted flour.
Combine sifted flour, salt and baking soda in a mixing bowl, whisking to combine.
Pour melted-but-cooled butter to a large mixing bowl with sugar. Mix with a hand mixer on low to combine.
Then, beat eggs and vanilla together and add it to the sugar butter mixture.
Add some of the sifted flour mixture to the wet mixture and mix on medium speed.
Then, alternating with the flour mixture, add buttermilk. Do this back and forth until the flour mixture and buttermilk have both been used up and are completely combined.
Cool the batter for 30 minutes to one hour in the refrigerator.
Using a 1 oz cookie scoop, scoop cookie dough onto parchment-lined baking sheets, giving the cookies at least 2 inches of space between them.
Bake for 15 minutes until the edges are just barely golden. Let them cool completely while you prepare the icing!
Sift powdered sugar to get rid of any lumps.
Combine the powdered sugar, lemon juice, hot water, vanilla extract and light corn syrup, stirring to combine. Equally divide the icing into 2 small bowls.
To the second bowl, add the cocoa powder, stirring until smooth.
Once your cookies have completely cooled after baking, frost the flat side of each cookie (yes, the side that was down on the baking sheet!) carefully with a butter knife or elevated spatula. You may need to ice them a couple times to tidy up the lines and have 2 colors that stand out.
However, don't worry if the colors run into each other; your cookies will still taste delicious! Let them dry completely on a wire rack before serving.