1. Combine Wet Ingredients (Cookies):

Combine the softened butter, granulated sugar, and orange zest in the bowl of an electric mixer.

Beat on medium speed until smooth.

Add the eggs and vanilla extract.

Beat again, scraping down the sides of the bowl halfway through, until everything is well combined.

2. Combine Dry Ingredients (Cookies): Sift together the all-purpose flour, baking powder, and kosher salt into a separate bowl.

3. Alternate Adding Dry and Wet Ingredients:

With the mixer on low speed, gradually add the dry ingredients to the butter mixture.

Alternating with the whole milk, until the dough just comes together. Be careful not to overmix.

4. Chill the Dough:

Divide the dough in half.

Flatten both halves into disks.

Place the disks in separate resealable plastic bags.

Refrigerate the dough until firm, about 2 hours. This chilling step is important for preventing the cookies from spreading too much during baking.

5. Preheat Oven and Prepare Baking Sheets: Preheat the oven to 350°F (175°C).

Line 2 baking sheets with parchment paper.

6. Roll Out and Cut the Dough:

Working with 1 disk of dough at a time (keeping the second disk refrigerated), lightly flour a work surface.

Roll the dough out to about ¼-inch thickness.

Use 2- to 3-inch butterfly cookie cutters to cut out as many cookies as you can.

7. Transfer and Bake:

Place the cut-out cookies on the prepared baking sheets, spacing them about 2 inches apart.

Bake until the cookies are just set but not browned, 8 to 10 minutes.

8. Cool:

Remove the cookies from the oven and let them cool for 5 minutes on the baking sheets.

Then transfer them to wire racks to cool completely before decorating.

Repeat with the remaining dough and scraps, rerolling only once for smooth cookies.

9. Make the Icing: While the cookies are cooling, make the icing.

Combine the sifted powdered sugar, whole milk, and pasteurized egg whites in the bowl of an electric mixer.

Beat on medium-high speed until the icing is thick and glossy.

Add more powdered sugar if the icing seems too thin. You want the icing to be stiff enough to hold its shape when you dip the cookies.

10. Divide and Color the Icing:

Divide the icing among 3 or 4 smaller bowls.

Add 2 to 3 drops each of red and orange food coloring to each bowl, scattering the drops over the surface of the icing.

11. Create the Swirled Effect: Drag a toothpick through the drops of food coloring a few times to make swirls. Don’t overmix. You want to create a marbled effect, not a solid color.

12. Dip and Dry:

Dip the top side of each completely cooled cookie in the icing.

Let the excess icing drip off.

Place the iced cookies on a rack to dry.

When the first bowl of icing becomes too muddled (the colors start to blend together too much), move on to the next bowl.

Let the icing dry completely, about 1 hour.

Serve and enjoy your beautiful and delicious Butterfly Sugar Cookies!