Place the yeast, vanilla paste and milk in a small bowl or cup and stir to dissolve yeast. Leave for 5 minutes or until foamy. Place the flour, sugar, eggs, yeast mixture and ¼ tsp fine sea salt in the bowl of an stand mixer fitted with a paddle attachment and mix until the dough comes together. Switch the paddle attachment for a dough hook and knead for 10 minutes or until smooth and elastic. Gradually add the butter, allowing piece of butter to become fully incorporated before adding the next. When all of the butter has been added knead until dough is smooth and glossy, roughly 3 or 4 minutes. Cover dough with a tea towel and leave in a warm place for 1 ½ to 2 hours or until doubled in size.
Knock back the dough and place on a tray covered with baking paper that has been lightly floured. Stretch and smooth the dough out to form a rough circle. Lightly cover with a tea towel and leave an hour our until doubled in size.
While the dough is rising preheat the oven to 220 celsius (425 Fahrenheit). When the brioche is ready to be baked top with the peach slices and blueberries in whatever pattern you desire. Brush the edges of the brioche with the egg wash and finally sprinkle with sugar. Bake for 15 to 20 minutes or until golden. Serve warm, dusted with icing sugar and a dollop of Greek yoghurt or mascarpone flecked with vanilla seeds.
Notes
Don't have peaches and blueberries? Top with your favourite fruit. Some combinations to try: apple and raspberries, strawberries, pear and slivered almonds, mixed berries.