1/4 cup plus 3 tablespoons finely ground fresh breadcrumbs
1/2 cup sugar
2 medium grapefruits
1/4 cup honey
1/4 cup extra virgin olive oil
1 1/2 cups all purpose flour
4 large eggs, at room temperature
2 teaspoons baking powder
1 teaspoon salt
Preheat the oven to 350F. Oil a 9-inch round cake pan with tall sides, and dust it with the 3 tablespoons breadcrumbs.
Using a grater, zest both grapefruits. Juice one of the grapefruits to yield 3/4 cup juice. In a small bowl, combine the zest, juice, and olive oil. Set aside.
n a large bowl, beat the eggs and salt with an electric mixture until frothy and light. Slowly beat in the sugar and honey, and continue to mix until pale and thick, about 2 minutes more.
In a separate bowl, sift together the flour, the remaining 1/4 cup breadcrumbs, and the baking powder. Then gradually beat the dry ingredients into the egg mixture. Fold in the citrus zest mixture just until incorporated.
Pour the batter into the prepared pan. Bake for 50 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let the cake cool in the pan on a wire rack for 10 minutes.
Then remove it from the pan and let it cool to room temperature.