Cake 3 cups all-purpose flour 1/2 teaspoon baking powder 1/4 teaspoon baking soda 1/2 teaspoon salt 1 cup (2 sticks) unsalted butter, at room temperature 3 cups granulated sugar 6 large eggs, at room temperature 1 teaspoon vanilla extract Grated zest of two oranges 1 cup sour cream, at room temperature
Syrup Grated zest of 1 orange 1 1/2 cups fresh orange juice 1 cup granulated sugar 3 tablespoons butter
To make the cake: Position a rack in the center of the oven and preheat to 325 degrees F. Butter and flour a 10-inch fluted tube or Bundt) pan, and tap out the excess flour.
Sift the flour, baking powder, baking soda and salt together; set aside.
Beat the butter and sugar in a large bowl with a hand-held electric mixer on high speed until light and fluffy, about 3 minutes. Beat in the eggs, one at a time, then the vanilla extract and zest. On low speed, add the flour in 3 additions, alternating with 2 additions of sour cream, beginning and ending with the flour. Beat until smooth, scraping down the sides of the bowl often with a rubber spatula. Spread evenly in the pan. Bake until a wooden skewer inserted in the center of the cake comes out clean, about 11/4 hours.
To make the syrup: Bring the orange zest, juice and sugar to a boil over medium-high heat and cook until reduced to a syrupy consistency, about 15 minutes.
Remove from heat and whisk in butter, 1 tablespoon at a time. Transfer the cake to a wire rack and cool for 10 minutes. Drizzle syrup over pound cake when you serve.
