Lizzie's Old Fashioned Cocoa Cake with Caramel Icing

INGREDIENTS

• 1/2 teaspoon vanilla extract
• 4 cups sugar
• 1/8 teaspoon baking soda
• 1 1/3 sticks (2/3 cup) butter, plus more to grease pans
• 1 cup milk
• 1 1/4 teaspoons baking soda
• 3 large eggs
• 1/4 teaspoon baking powder
• 2 cups all-purpose flour, plus more to grease pans
• Special equipment: candy thermometer
• Cooking spray
• 1 teaspoon salt
• 2/3 cup cocoa
• 1 teaspoon vanilla extract
• 1 stick (1/2 cup) butter
• 1 2/3 cups sugar