Makes 8 buns.
Ounce units are weight ounces (not fluid ounces).

Sponge Starter:
4 oz yeast starter
6 oz AP flour
6 oz warm milk

Final Ingredients:
12 oz AP flour
4 oz warm milk
1 egg, beaten
0.4 oz melted unsalted butter (~1/4 cup)
0.4 oz salt
0.4 oz sugar

Optional:  melted butter or egg wash for brushing.

Directions:
1) Mix up sponge starter the night before.
2) The next morning add final ingredients.
3) Knead for a few minutes in a stand mixer.
4) Form into a ball.
5) Place into an oiled bowl and cover.
6) When doubled in size, punch down, reform, and divide into 8 equal pieces (~4.5 oz each).
7) Form pieces into balls and place on parchment lined baking sheet.
8) Brush with melted butter or egg wash. (Optional)
9) Bake @400 deg F for 30-35 minutes until done.