Step 1Wash the oranges and simmer them, unpeeled, in water to cover for 2 hours. Cool, cut them open and remove the seeds. Puree the oranges, including the peel, in a food processor.Step 2Heat oven to 400 degrees. Beat the eggs in a food processor or large bowl. Add the remaining ingredients, including the orange puree, and mix thoroughly. Pour into a buttered and floured cake tin, with a removable base if possible.Step 3Bake for 45 minutes to 1 hour, or until a knife inserted in the center comes out clean. Cool in the pan before turning out.