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
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
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 1 1/4 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.