Put the orange and the lemon in a saucepan, and cover with water. Bring to a boil over medium-high heat; then reduce the heat to medium and simmer for 30 minutes. Drain, and cool.

Meanwhile, toast the almonds. Preheat the oven to 325°F, and set a rack in the middle position. Put the almonds on an ungreased sheet pan, and bake until they look golden and smell warm and toasty, 10 to 15 minutes. Set aside to cool completely. When the almonds are cool, pulse them in a food processor until finely ground, the texture of coarse sand. Set aside.

Set the oven to 350°F, and grease a 9-inch round springform pan.

When the citrus is cool, cut the lemon in half, and scoop out and discard the pulp and seeds. Cut the orange in half, and discard the seeds. Put the lemon rind and orange halves in the food processor – there’s no need to wash it after grinding the almonds – and process to chop finely, almost to a coarse paste.

In a small bowl, whisk together the flour and baking powder.

Combine the eggs and salt in a mixing bowl. Beat until foamy. Gradually beat in the sugar. Fold in the flour mixture. Add the citrus, almonds, and olive oil, and beat on low speed to just incorporate. Do not overmix. Pour the batter into the prepared pan, and bake for about 1 hour, or until a toothpick inserted in the center comes out clean. Cool the cake in its pan on a wire rack. Remove the sides of the pan. Before serving, dust the cake with confectioners’ sugar.

From Orangette who adapted it from a recipe from the Boonville Hotel