Lemon Poppy-Seed Cake

INGREDIENTS

1 1/2 cups

whole-wheat pastry flour, (see Note)

1 cup

all-purpose flour

1/4 cup

poppy seeds,toasted (see Tip)

1 1/2 tsp

baking powder

1/2 tsp

baking soda

1/4 tsp

salt

1 cup

buttermilk, (see Tip)

1/4 cup

canola oil

1 tsp

vanilla extract

2 tbsp

freshly grated lemon zest

2 tbsp

lemon juice

large eggs, at room temperature (see Tip)

large egg whites, at room temperature

1 1/4 cups

sugar

3/4 cup

confectioners’ sugar, plus more for dusting

3 tbsp

lemon juice

1 tbsp

water