Ingredients

Equipment Needed

• •Stand mixer or hand mixer
• •Two rimmed baking sheets
• •Parchment paper
• •1/4 cup measure or large cookie scoop
• •Wire cooling rack
• •Small offset spatula or butter knife
• •Fine-mesh sieve for sifting

Instructions

1. 1

   Prepare dry ingredients

   Whisk together the flour, baking powder, and salt in a medium bowl. Set aside. Preheat your oven to 350°F and line two baking sheets with parchment paper. These cookies spread, so you'll want room between them.

2. 2

   Cream butter and sugar

   In a stand mixer fitted with the paddle attachment (or using a hand mixer), beat the softened butter and sugar on medium-high speed until pale and fluffy, about 3 minutes. The mixture should look almost white and feel light when you scrape the bowl. This aeration creates the cookie's signature tender crumb.

   Truly softened butter leaves a slight indent when pressed but doesn't feel greasy. Cold butter won't cream properly; melted butter creates dense cookies.
3. 3

   Add eggs and wet ingredients

   Add the eggs one at a time, beating well after each addition. Scrape down the bowl. Mix in the milk, sour cream, vanilla extract, and almond extract until just combined. The batter may look slightly curdled at this stage. That's normal and will smooth out when you add the flour.

4. 4

   Incorporate flour

   With the mixer on low speed, gradually add the flour mixture. Mix only until the flour disappears. The batter will be thick and sticky, closer to muffin batter than typical cookie dough. Do not overmix or the cookies will turn tough. Stop the moment you see no more dry streaks.

5. 5

   Portion the batter

   Using a 1/4 cup measure or large cookie scoop, drop mounds of batter onto the prepared baking sheets, spacing them 3 inches apart. You'll fit about 4 per standard sheet. Use the back of a spoon dipped in water to gently spread each mound into a round about 3 inches across and 1/2 inch thick. Don't worry about perfection. The oven will smooth the edges.

   For bakery-sized cookies, use a full 1/4 cup of batter. For more modest portions, use 3 tablespoons and reduce baking time by 2 minutes.
6. 6

   Bake until set

   Bake for 13 to 15 minutes, rotating the pan halfway through. The cookies are done when the edges are just barely golden and the tops spring back when lightly pressed. The centers may look slightly underdone. This is correct. They will firm as they cool. Pull them a minute early rather than a minute late.

   Overbaked black and whites turn dry and crumbly within a day. The goal is moist and cakey, not crisp or browned.
7. 7

   Cool completely

   Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack. Cool completely, flat side up, before icing. This takes about 30 minutes. Resist the urge to rush this step. Warm cookies will cause the fondant to run and pool unevenly.

8. 8

   Make vanilla fondant

   In a medium bowl, whisk together the sifted powdered sugar, corn syrup, and 2 teaspoons vanilla extract. Add hot water one tablespoon at a time, stirring constantly, until you reach a thick but pourable consistency. The icing should coat the back of a spoon thickly and drip off in a slow ribbon. Test it on a plate first. It should spread easily but set firm within a minute.

9. 9

   Make chocolate fondant

   Transfer half the vanilla fondant to another bowl. Sift the Dutch-process cocoa powder into it and stir until smooth. The cocoa will thicken the icing. Add an additional tablespoon of hot water and stir until you match the consistency of the vanilla side. Both icings should flow the same way.

   Dutch-process cocoa produces a richer, darker color than natural cocoa. For the most authentic NYC bakery look, Dutch-process is essential.
10. 10

    Ice the cookies

    Turn the cookies flat-side up. This is the icing surface, smooth and even. Using a small offset spatula or butter knife, spread vanilla fondant over one half of each cookie, creating a clean line down the center. Work from the middle outward to avoid pushing icing off the edge. Let the vanilla set for 2 minutes, then spread chocolate fondant on the other half, meeting the vanilla at the center line. The slight gap between applications helps create a clean division.

11. 11

    Set the icing

    Let the iced cookies rest at room temperature for at least 30 minutes until the fondant sets completely. It should feel dry to the touch and hold a fingerprint without sticking. The surface will develop that characteristic semi-matte shine that marks a proper black and white.

Chef Tips

• •The sour cream is non-negotiable. It provides moisture, tang, and tenderness that no other ingredient can replicate. Full-fat only. Low-fat versions will produce a drier cookie.
• •Let all dairy ingredients come to room temperature before mixing. This takes about an hour. Cold ingredients won't emulsify properly and can cause the batter to break.
• •Sift your powdered sugar for the icing, even if the package claims it's pre-sifted. Lumps will show in the finished fondant and there's no fixing them once the icing sets.
• •If your fondant starts to set before you've finished icing, place the bowl over a pot of barely simmering water and stir until it loosens. Work in small batches to keep the icing pliable.
• •The flat bottom of the cookie becomes the icing surface. This is traditional and practical. The domed top would cause icing to run off the sides.
• •Store at room temperature in a single layer, loosely covered with plastic wrap. The refrigerator will make the icing sweat. Properly stored, they keep 3 to 4 days.

Advance Preparation

• •Cookie batter can be portioned onto parchment-lined sheets, covered with plastic wrap, and refrigerated overnight. Let sit at room temperature for 15 minutes before baking. Add 1-2 minutes to baking time.
• •Baked, un-iced cookies can be stored in an airtight container at room temperature for up to 2 days or frozen for up to 2 months. Thaw completely before icing.
• •Fondant icing is best made fresh. It can be prepared up to 2 hours ahead and kept at room temperature, covered with plastic wrap pressed directly against the surface. Rewarm gently over simmering water if it stiffens.
• •Fully iced cookies freeze beautifully. Place in a single layer on a sheet pan, freeze until solid, then stack between layers of parchment in an airtight container. Thaw at room temperature for 2 hours before serving.

Frequently Asked Questions

Nutrition Information

1 cookie (about 67g)