For the waffles, preheat a waffle maker to a medium setting and preheat the oven to 140c/275f/gas 1. Place a large wire rack onto a baking tray and keep it warm. Mix the flour, baking powder, salt and granulated sugar in a bowl. Whisk in the eggs, milk and butter. Ladle some of the batter into each well of the waffle make, close the lid and cook for five minutes, or until golden-brown and crisp. Repeat the process until the batter is used up. Keep the waffles warm on the baking tray in the oven.For the hot chocolate sauce, melt the chocolate in a bowl set over a pan of simmering water (ensure the bottom of the bowl does not touch the water). Stir in the sugar. Serve waffles on a plate with ice-cream and drizzle sauce on top.