In a shallow bowl, whisk together the eggs double cream, sugar and vanilla. Evenly coat the brioche slices. Place the a frying pan on a medium heat and melt in the butter. Then place the first slice in a the pan. Spread over an even layer of blueberry jam, followed by blueberries and a sprinkle of cinnamon.
Finish with the other slice of brioche and flip, until golden on each side. Meanwhile whip the other double cream, slowly pouring in the maple syrup as you go.
Sprinkle over icing sugar and serve with the maple cream.