The New Black-and-White Cookie

1. Preheat the oven to 350°F. Line two baking sheets with parchment paper.

2. In the bowl of an electric mixer fitted with the paddle attachment, cream the butter with the sugars on medium speed until light and fluffy, 3 to 4 minutes. Add the egg and vanilla extract and mix to combine, scraping well to ensure it is incorporated.

3. In a medium bowl, whisk the flour with the salt, baking soda and baking powder to combine. Add the flour mixture to the mixer and mix on low speed until incorporated, 1 to 2 minutes.

4. Remove half the dough (about 2 cups) from the mixer and transfer it to a large bowl.

5. Add the cocoa powder to the dough remaining in the mixer; mix to combine. Add the white chocolate chips, if using, and mix to incorporate.

6. Add the semisweet chocolate chips, if using, to the reserved dough in the bowl and mix with a spatula to combine.

7. Divide the chocolate and vanilla doughs into tablespoon-sized scoops. Take a scoop of each flavor, press them together and roll lightly. Transfer to the prepared baking sheet and press lightly. Repeat with the remaining dough, leaving at least ½ inch between each cookie on the baking sheet.

8. Bake the cookies until they are golden around the edges, 7 to 9 minutes. Cool before serving. The cookies can be kept for up to a week at room temperature in an airtight container.