Pre-heat the oven to 350 degrees F and butter and flour your cake pan. Wash oranges thoroughly to remove pesticide and wax residue. Slice tops and bottoms off of the oranges to remove the thickest part of the skin and discard. Chop oranges into chunks and discard the seeds. In a food processor, process the oranges into a chunky puree. Add the olive oil slowly and continue to process until it is well blended.