1920's recipe for chocolate cake

Ingredients

• 1 ¾ cups all-purpose flour
• 1 ½ cups granulated sugar
• ¾ cup unsweetened cocoa powder
• 2 teaspoons baking soda
• 1 teaspoon baking powder
• 1 teaspoon salt
• 2 large eggs
• 1 cup whole milk
• ½ cup vegetable oil
• 2 teaspoons pure vanilla extract
• 1 cup boiling water
• ½ cup unsalted butter, softened
• ⅔ cup unsweetened cocoa powder
• 3 cups powdered sugar
• ⅓ cup whole milk
• 1 teaspoon pure vanilla extract