I made this lemon-lime yogurt cake on a whim a few years ago because I wanted to try substituting butter. Very quickly it became a favorite! It's super moist and has a different texture from usual pound cakes. Sometimes I make it all lemon and also add half sour cream, which makes it even better.
Spray or butter a 10x4-inch (27x9cm) loaf cake pan and line it with a strip of parchment paper, covering the bottom and two short sides. The long sides will be greased but not lined.
In a large bowl, beat 1 ¼ cups sugar, ½ cup plain Greek yogurt, ½ cup sour cream, ½ cup vegetable oil, and 3 eggs until smooth and lump-free, about 3 minutes. Add ½ teaspoon lemon zest and ½ teaspoon lime zest and mix for 1 more minute.
Add dry, sifted ingredients: 1 ½ cups all-purpose or cake flour, 2 teaspoons baking powder, and ½ teaspoon salt in 2 parts, and beat just to incorporate well. Don't overbeat, or the cake will be tough. You can sift them before in a separate bowl or have the ingredients measured and sift them directly over the butter mixture when prompted (my choice).
Stir in 1 tablespoon fresh lemon juice, 2 teaspoons fresh lime juice and ½ teaspoon vanilla extract until well incorporated. Don't beat at this time.
Pour batter into the prepared pan and bake for 45-50 minutes, until a toothpick inserted comes out clean. The surface will be shiny and possibly cracked, not as dry as regular cakes.
Let cool on a wire rack.
To remove the cake from the pan, run a smooth-bladed knife along the sides to unstuck any parts. Carefully lift the cake, helping yourself by lifting the parchment paper.
For the citrus glaze:
Beat ¾ cup powdered sugar with 2 tablespoons lime and lemon juice until no lumps remain. Add juice in batches, so you can make it as thick or runny as you wish.
Pour over room temperature cake and decorate with lemon and lime zest before it sets.
Notes
Baking time: Consider that all ovens and pans are different, even if they look similar. The baking time in my recipes is as accurate as possible, but it might take you more or less time. You can use a thermometer to check that your oven is at the right temperature. I recommend keeping track of how your oven works and what tiny details you might need to adjust. Yogurt: I found that different brands make a slight difference in the cake's texture, so you might need to find the one you like the most. I don't recommend using low-fat yogurts.Storing: this loaf cake keeps very well for a few days. I recommend covering it in plastic wrap so it doesn't dry out. It can be frozen up to a month.