2 cups cake flour
1 teaspoon baking soda
1 teaspoon ground ginger
1/4 teaspoon fine salt
1 cup canned pure pumpkin puree
1/4 cup reduced-fat buttermilk
1 teaspoon pure vanilla extract
4 tablespoons unsalted butter, at room temperature
1 packed cup light brown sugar
2 large eggs, at room temperature
1/4 cup finely chopped crystallized ginger
Confectioners' sugar, optional