Roti Ham dan Keju

Bahan-bahan (4 porsi)

• 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
• 2 teaspoons Japanese mayonnaise Kewpie
• 6 oz thinly-sliced deli ham
• 8 slices cheddar cheese
• 1/2 small yellow onion (sliced)