For the cake:
2 cups all purpose flour
1 3/4 teaspoons baking powder
1 teaspoon kosher salt
1 2/3 cups granulated sugar
2 large eggs
1 cup whole milk
3/4 cup canola oil
1 tablespoon grated pink grapefruit zest
1 teaspoon vanilla extract
For the grapefruit syrup
1 cup strained fresh pink grapefruit juice
2/3 cup granulated sugar
3/4 cup powdered sugar
1 tablespoon plus 1 teaspoon fresh pink grapefruit juice
pomegranate seeds (optional)
Preheat the oven to 350 degrees. Grease a 10×4 inch loaf pan or two smaller loaf pans.
Sift the flour, baking powder and salt together and set aside.
In another bowl combine the sugar and eggs in a mixing bowl with an electric mixer fitted with the whisk attachment. Mix for about 3 minutes or until the mixtures is thickened and the whisk leaves a trail.
Next, beat in the milk, oil, grapefruit zest and the vanilla. Reduce the speed to low and add the flour mixture, mixing just to incorporate; scrape the sides of the bowl as needed.
Pour the mixture into the pan. Put the pan on a small baking sheet and bake for 1 hour. Midway through baking, turn the pan around once or twice so that the cake colors evenly. When ready, a skewer inserted in the center of the cake should come out with just a few moist crumbs clinging to it.
Combine the citrus juice and sugar (for the syrup) in a saucepan and cook over medium heat just until the sugar has dissolved. Set aside.
As soon as the cake is removed from the oven, poke deep holes ever 3/4 inch all over the top of the cake using a skewer. Immediately begin brushing the syrup over the cake. Continue with all of the syrup. Let the cake cool for 10 minutes.
Unmold the cake onto a cooling rack, turn it right side up, and let cool to room temperature.
Stir the powdered sugar and grapefruit juice together in a bowl until smooth. Drizzle over the cake, letting it run over the sides. Slice and serve with pomegranate seeds (optional).