This is the one I make using oranges.  It is from the Barefoot Contessa foodnet work site.

It is beyond belief!!!  I have to make at least 4 of the loaf cakes because everyone loves it.

• 1/2 lb unsalted butter, at room temperature
• 2 1/2 cups granulated sugar, divided
• 4 extra-large eggs, at room temperature
• 1/3 cup grated orange zest (6 oranges)
• 3 cups all-purpose flour
• 1/2 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1 teaspoon kosher salt
• 3/4 cup freshly squeezed orange juice, divided
• 3/4 cup buttermilk, at room temperature
• 1 teaspoon pure vanilla extract

Directions

1. 1Preheat oven to 350°.
2. 2Butter and flour 2 loaf pans.
3. 3Cream butter and 2 cups of sugar in a bowl.
4. 4Mix in eggs, one at a time; add zest.
5. 5Sift flour, baking powder, baking soda and salt together.
6. 6In another bowl mix 1/4 cup orange juice, buttermilk and vanilla.
7. 7Add flour and buttermilk mixture aternately to the batter, beginning and ending with flour.
8. 8Divide between 2 pans and smooth the tops.
9. 9Bake for 45 minutes or until tester comes out clean.
10. 10Cool for 10 minutes.
11. 11Make syrup while cake is baking.
12. 12Syrup consists of remaining 1/2 cup sugar and 1/2 cup orange juice.
13. 13Cooks these two together over low heat till the sugar is desolved.
14. 14Spoon over cakes and then allow them to cool completely.
15. 15You may glaze these cakes (after cooling) with a simple glaze but I don't usually.

It's really a good one.

Deb