Place partially defrosted blueberries in a saucepan (microwave if necessary). Add sugar and simmer for around 20 to 30 minutes until slightly thickened. Cool a little before use. The sauce will be slightly runny, it is part syrup, part sauce! If a thicker sauce is desired, cornstarch can be added.

Beat eggs until well mixed. Add oil, milk and vanilla. Beat until combined. Add flour, sugar and baking powder. Mix until just combined.

Preheat waffle maker, brush with melted butter before each waffle. Use around 1/5 to 1/4 of the batter for each waffle. While waffles are cooking whip cream with the icing sugar. Serve waffles with the blueberry sauce, cream and dusted with icing sugar if desired.