Bread Dough – ▢2 1/2 tablespoons granulated sugar – ▢1 teaspoon active dry yeast – ▢2 1/4 cups bread flour – ▢1/4 teaspoon salt – ▢1 egg – ▢3/4 cup warm milk – ▢1 1/2 tablespoons unsalted butter Bread Filling – ▢2 teaspoons Japanese mayonnaise Kewpie – ▢6 oz. thinly-sliced deli ham – ▢8 slices cheddar cheese – ▢1/2 small yellow onion (sliced)