In a saucepan
, cook the cranberries with the sugar
until they render
some juice, about 5 minutes. Let cool to room temperature.
On a work surface, use a knife to cut the peel from the oranges. Cut between the membranes and divide into sections (supremes).
When ready to serve, pour a spoonful of the cranberry mixture in a glass with a few orange supremes. Top with prosecco.