Plum brioche buns

Crumble

• 50 g baker's flour
• 50 g white sugar
• 40 g unsalted butter

Brioche

• 250 g milk
• 100 g white sugar
• 10 g dried instant yeast
• 520 g baker's flour, plus extra to dust
• 1 tsp natural vanilla extract
• 2 eggs, separated
• 80 g unsalted butter, cut into pieces, softened
• 1 pinch sea salt
• extra virgin olive oil, to grease
• 300 g fresh blood plums (3-4), stones removed, cut into thin wedges (see Tips)