Step 1

Preheat the oven to 250 degrees. Place all citrus in a pot with enough water to cover the fruit. Bring to a boil, then lower the heat and simmer for 30 minutes to soften the fruit. Pour out the water and let fruit cool to room temperature. You can run cold water over the fruit to speed up the cooling process. Remove seeds and then place the fruit, with skin, in a food processor and puree until smooth. While processing, slowly trickle in olive oil to make a paste. Remove paste and set aside; wipe out food processor.

Step 2

Place almonds on a baking sheet and toast in the oven for 20 minutes or so. To test, break an almond in half and check for a toasted color. Once they’re toasted, remove almonds from the oven and let cool.

Step 3

Preheat the oven to 350 degrees. When the almonds have cooled, add them to the food processor and pulse until they reach a fine texture similar to sand. Add the all-purpose flour and baking powder to the food processor, and pulse to combine.

Step 4

In a bowl, whisk eggs with salt until foamy, then add sugar a little at a time while whisking. (Alternatively, use a stand mixer to whisk the eggs, then slowly add sugar.) Whisk until sugar is mostly dissolved.

Step 5

Fold in orange paste. Then fold in flour mixture. Do not overmix. Pour into one 10-inch or two 5-inch springform pans and bake for 45 minutes to 1 hour, or until a toothpick inserted in the center of the cake comes out clean. Remove from the oven and let cool on a wire rack until the sides pull away.