Sift Dry Ingredients: In a medium bowl, sift together the flour, baking soda, and salt. Set aside.

Cream Butter and Sugar: In a stand mixer or using a hand mixer, beat the room-temperature butter on medium speed for 1 minute. Gradually add the sugar and continue beating for 5-7 minutes until the mixture is light, fluffy, and pale yellow.

Add Eggs: Beat in the eggs one at a time, ensuring each egg is fully incorporated before adding the next. Mix in the vanilla extract.

Combine Wet and Dry Ingredients: On low speed, alternate adding the dry ingredients and buttermilk in three parts:

Start with ⅓ of the flour mixture.

Add ½ of the buttermilk.

Repeat, ending with the flour mixture. Mix just until combined—do not overmix.

Shape the Dough: Use a cookie scoop or tablespoon to portion the dough into 24 equal balls (about 2 tablespoons each). Place them on a parchment-lined baking sheet.

Chill: Cover the dough balls with plastic wrap and refrigerate for 2-4 hours. This step is crucial to prevent spreading and achieve the perfect dome shape.

Preheat Oven: Preheat your oven to 375°F (190°C) and line baking sheets with parchment paper or silicone mats.

Flatten Slightly: Remove the dough from the fridge. Gently press each ball with your palm to create a uniform thickness (about ½ inch thick).

Bake: Place the cookies on the prepared sheets, spacing them 3 inches apart. Bake for 10-12 minutes, rotating the pans halfway through, until the edges are lightly golden and the centers are set.

Cool: Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.

Vanilla Icing: In a medium bowl, whisk together powdered sugar, milk (start with 2 tablespoons), and vanilla extract until smooth. Add more milk, 1 teaspoon at a time, until the icing is thick but spreadable. Add lemon juice for shine if desired.

Chocolate Icing: In another bowl, whisk together powdered sugar, cocoa powder, milk (start with 2 tablespoons), and vanilla extract. Adjust the consistency with more milk as needed. For a deeper black color, add 1-2 drops of black food coloring.

Divide the Cookies: Use a knife or offset spatula to spread the vanilla icing on one half of each cookie and the chocolate icing on the other half. Aim for a clean, straight line down the middle.

Let Set: Allow the icing to set at room temperature for 1-2 hours or until firm.

Presentation: Arrange the cookies on a dark platter, dust with powdered sugar for a starry effect, and serve with coffee, tea, or milk.