Preheat oven to 350° (F). Line a large baking sheet with parchment paper; set aside.
Sift together flour, baking soda and salt in medium-sized bowl.
In small measuring cup whisk together buttermilk and vanilla.
In the body of a stand mixer fitted with the paddle attachment beat butter, sugar, and lemon zest together for about 3 minutes, or until light and fluffy.
Add eggs - one at a time - to butter/sugar mixture, and beat until blended.
Gradually beat in flour mixture one cup at a time, adding in the buttermilk mixture between each cup of flour; mix until just smooth.
Spoon batter in 1/4 cup size servings onto prepared baking sheet.
Place pan in the oven and bake on the middle rack for 15-17 minutes, or until the tops are lightly golden and spring back when touched.
Place on a cooling rack, and allow to cool completely (!!!) before icing.
For the Black and White Frosting:
Place softened butter and cream cheese into the bowl of a stand mixer that has been fitted with the paddle attachment.
Turn the mixer on (medium setting) and cream the butter and cream cheese until it's smooth and has lightened in color; about 2 minutes.
Add confectioner's sugar, 1 cup at a time. After each cup has been incorporated, turn the mixer onto high speed and beat for about 15 seconds; this will lighten the frosting.
Add vanilla and salt and combine until well-incorporated.
Add buttermilk, a tablespoon at a time, until the frosting has reached the preferred consistency.
Divide frosting into two bowls. In one of the bowls add cocoa powder and mix until well combined.
Once cookies are cooled spread 1 heaping tablespoon of chocolate icing on half of the cookie (on the flat side!), then spread 1 tablespoon of the white frosting on the other side. Don't stress if they don't look perfect or if the colors blend! They'll still taste great :)
Tried it and loved it?Snap a picture and share it with me on Instagram @Bakerbynature and by using the hashtag #BakerByNature