Use a vegetable peeler or zester to remove the peels from all of the oranges, avoiding peeling the bitter white pith. Place the orange peels and vanilla beans in a large jar and cover with alcohol. Allow to steep for one week somewhere dark, like a closet or cabinet.
Strain the infused vodka into a large bowl and discard the orange peels and vanilla beans. Add one cup of simple syrup to the vodka and stir. Taste for sweetness, adding more simple syrup as desired. Use a funnel to bottle the vanilla-orangecello and set aside in a dark area for one more week for the flavor to mellow. Chill thoroughly in the freezer before serving.