Mix bread flour, sugar, salt, dry yeast, milk, egg, and butter to make the dough.
Let the dough rise for the first fermentation.
Mix the soboru topping ingredients to make the soboru crumble.
Divide the dough and shape it into balls.
Place the soboru crumble on top of each round dough.
Let it rise again for the second fermentation.
Bake for 15 minutes in a preheated oven at 180°C.