• ¾ cup white sugar
• ¼ cup cocoa
• 3 tablespoons all-purpose flour
• 2 cups milk
• 1 tablespoon butter, softened
• 2 teaspoons vanilla

Whisk sugar, cocoa, and flour in a medium bowl until no lumps remain. Pour in milk and whisk until well combined. Transfer mixture to a saucepan; cook and stir over medium heat until it thickens to a gravy consistency, 7 to 10 minutes. Remove from heat; stir in butter and vanilla.