6 tablespoons unsalted butter (softened, plus extra for buttering the pan)
1 cup (packed) light sugar
2 large eggs (at room temperature)
3/4 cup unsweetened pumpkin (purée)
1 1/2 tablespoons fresh lemon juice
3/4 cup whole wheat pastry flour
1/2 cup unbleached all-purpose flour
1 1/4 teaspoons baking powder
1 teaspoon ground cinnamon
1 teaspoon ground ginger
1/8 teaspoon ground cloves
1/8 teaspoon salt
1/3 cup finely chopped crystallized ginger
1/3 cup finely chopped dates
  Vanilla Crème Anglaise or ice cream (optional)