Toss together the berries, flour, sugar and vanilla extract and place in an ovenproof dish.
Cut the brioche slices into triangles, removing the crusts if you like. Butter both sides of the brioche and arrange on top of the berries. Cover the dish with foil and then bake in a preheated oven, 220°C (425°F), Gas Mark 7, for 10 minutes. Uncover and cook for a further 5 minutes until golden and crisp. Serve with vanilla ice cream.