Slice baguette into 11/2-in (3.5-cm) thick rounds. Using a serrated knife, cut through the middle of bottom crusty side of each round to make a slit large enough to hold a square of chocolate. Widen slits and tuck a piece of chocolate into each. Place in a 9×13-in. (3-L) baking dish, bunching bread close together to fit. In a bowl, whisk eggs with milk, sugar, vanilla, cinnamon and salt. Pour over bread. Turn bread over to fully soak up egg mixture. Cover and refrigerate at least 1 hour or overnight.
Preheat oven to 450F (230C). Generously brush a large wide baking sheet with some melted butter. Space soaked bread on baking sheet so pieces aren’t touching. Bake in centre of oven for 8 min. Remove from oven, brush tops of bread with remaining melted butter, then turn slices over. Continue to bake until crusty and deep golden, 8 to 10 more min. Place toasts on plates. Drizzle with chocolate sauce, sprinkle with peel and icing sugar.
Nutrition (per serving)
Each piece crisps and browns so well in the oven you’d think it was done in a frying pan.