Brioche Hot Dog Buns

1/4 cup (60ml) warm milk

1/4 cup (60ml) warm water

2.0 tsp (5g) active dry yeast

1.75 cups (260) bread flour

1 Tbsp (10g) granulated sugar

1.5 (5g) tsp fine sea salt

1 egg

1 egg yolk

1.5 (20g) Tbsp softened unsalted butter