For the vanilla batter:
- ½ cup (113 gm) unsalted butter, at room temperature
- ½ cup (100 gm) sugar
- ¼ cup (50 gm) brown sugar
- 1–1/2 large eggs, at room temperature (save the other half for the chocolate batter)
- ¾ teaspoon vanilla extract
- 1/4 teaspoon lemon zest (optional)
- ¾ cup (100 gm) all-purpose flour
- 3/4 teaspoon baking powder
- ¼ teaspoon salt
- 6 tablespoons (3 ounces) whole fat buttermilk, at room temperature
For the chocolate batter:
- ½ cup (113 gm) unsalted butter, at room temperature
- ½ cup (100 gm) sugar
- ¼ cup (50 gm) brown sugar
- 1–1/2 large eggs, at room temperature
- ¾ teaspoon vanilla
- ¼ cup (20 gm) dark cocoa powder
- ½ cup (65 gm) all-purpose flour
- 3/4 teaspoon baking powder
- ¼ teaspoon salt
- 6 tablespoons (3 ounces) whole fat buttermilk, at room temperature