Traditional Chinese Steamed Cake (Fa Gao)

INGREDIENTS

• 2 teaspoons active dry yeast
• 1/2 cup warm water
• 1 egg
• 1/3 cup melted butter
• 1/4 teaspoon vanilla extract
• 1/2 cup milk
• 1 1/2 cups cake flour
• 1/2 cup cornmeal
• 1/3 cup superfine sugar
• 1/2 teaspoon salt
• 1/4 cup raisins (optional)