Preheat oven to 180°C/160°C. Make a hole in the middle of each hot-cross bun and insert an Easter egg into each. Place buns onto a large baking tray lined with baking paper. Bake for 8-10 minutes or until buns are warm. Remove from oven.
Place chocolate into a heatproof bowl. Microwave for 1-2 minutes, in 30 second bursts, until melted. Stir using a metal spoon.
Arrange 7 buns to form a circle on a large serving plate. Stack 2 buns in the centre (to help hold the tower). Dip one side of a hot-cross bun into the melted chocolate and stack onto the bun base. Continue dipping and stacking to form a tower of hot-cross buns, finishing with 1 bun at the top.
To make pink icing, place icing sugar into a bowl, gradually add water to form a smooth slightly runny consistency. Gradually drop in the food colouring and stir to form a pale pink icing. Drizzle icing over the hot-cross bun tower.
To decorate, sprinkle with silver cachous and small Easter eggs.