In a saucepan, combine 2 cups of the blueberries with the sugar. Bring to a boil and let simmer over low heat for about 7 minutes, or until the liquid thickens into a syrup. (This will take about 15 minutes if you’re using frozen blueberries.)
Add the remaining blueberries and cook for 1 minute. Let cool.
If you use frozen blueberries, the compote will be a little runnier.