Step 1

Preheat oven to 350°F. Line two baking sheets with parchment paper or silicone baking mats.

Step 2

Whisk together flour, baking soda, baking powder and salt in a bowl. Stir together buttermilk, vanilla and lemon zest in a small bowl.

Step 3

Beat together butter and sugar in a large bowl with an electric mixer or a stand mixer fitted with whisk attachment until pale and fluffy, about 3 minutes. Add egg and mix again until well combined.

Step 4

Alternate adding flour and buttermilk mixture on a low speed until batter is well combined and smooth.

Step 5

Using a cookie scoop, place batter about 2 inches apart on cookie sheet. Dipping your pointer finger in water, smooth the edges of each cookie. (This step is optional, but will ensure a slightly more even shape).

Step 6

Bake 15-17 minutes, until tops are puffed and golden.

Step 7

Remove cookies from sheet and place on cooling rack to cool for at least 1 hour before icing.

Step 8

To make icing: whisk together confectioners sugar, corn syrup, vanilla, and 2 Tbsp milk in a small bowl until smooth. Transfer half of icing to another bowl and stir in cocoa, adding more milk, 1 tsp at a time, until consistency is the same as white icing.

Step 9

Turn cookies upside down. Place icing scraper tool (or parchment paper) over half of each cookie and spread the uncovered halves with white frosting using a small offset spatula. Allow to set 10-15 minutes. When icing has set, frost the other side of the cookies with chocolate icing. Yes, you should start with the white icing.

Step 10

Allow to set another 10-15 minutes until serving.

Step 11

Store in an airtight container for 2-3 days.