Blueberry Lemon Pound Cake

1 cup (2 sticks) unsalted butter, at room temperature
1 cup sugar
4 large eggs, separated
1 tablespoon finely grated lemon zest
1 teaspoon pure vanilla extract

3/4 cup sour cream
1 1/2 cup all-purpose flour
1 teaspoon baking powder
Pinch of salt
1 3/4 cups blueberries, lightly rinsed and dried

Let the loaf rest in the pan on a rack for an hour before turning it out of the pan. Then place it back on the rack and allow it to cool completely. For a real treat, top a slice of this sumptuous pound cake with a generous scoop of the Blueberry Sorbet. Preheat oven to 350 degrees. Butter a 9x5x2 3/4-inch loaf pan. Line the bottom with a piece of parchment or waxed paper and butter the paper. Lightly dust the pan with flour, shaking out the excess. In a mixing bowl, cream 1 cup of butter and the sugar with an electric mixer until light and fluffy. Add the egg yolks, lemon zest and vanilla extract; beat until smooth. Add the sour cream and beat to combine. Sift the flour, baking powder and salt together, add to the butter mixture in three batches, stirring with a wooden spoon until just combined. Beat the egg whites in a bowl until they hold soft peaks. Stir a third of the whites in to the batter to combine. Fold the remaining whites into the batter with a rubber spatula until just combined. Do not over mix. Fold the blueberries into the batter. Scrape into the prepared pan. Bake for 35 minutes. Reduce the oven temperature to 325 degrees and bake 45 minutes longer or until pound cake is golden brown and a toothpick comes out clean when inserted in the center. Cool the cake in the pan on a rack for at least 1 hour. Yield: 1 loaf.