Sift the flour into a bowl, then stir in the sugar. Add the egg and a little milk, and whisk to make a stiff batter. Beat in the remaining milk.
Heat a little butter or oil in an 18 cm (7 inch) pancake pan or heavy-based frying pan until it starts to smoke. Pour off the excess and pour a little batter into the pan, tilting it until the base is coated in a thin layer. (Or, if you prefer, use a small ladle to measure the batter into the pan.) Cook for 1–2 minutes until the underside begins to turn golden.
Flip the pancake with a palette knife and cook for a further 30–45 seconds on the second side. Slide the pancake out of the pan and make the remaining pancakes, greasing the pan as necessary. Set the pancakes aside while you make the sauce.
Melt the butter in a frying pan with the light muscovado sugar, then add the Rubis chocolate velvet ruby, liqueur or port.
Divide the chocolate squares among the pancakes, then fold into halves, then quarters, and slide into the pan. Warm through for a couple of minutes and serve each pancake drenched in sauce.