SEVILLE ORANGE BREAD AND BUTTER PUDDING

1 Waitrose & Partners Richly Fruited Loaf, all but the end slices • 30g salted butter, very soft • ½ tsp ground cinnamon • 3 medium Clarence Court Burford Brown Eggs • 2 tbsp golden caster sugar, plus ½ tsp • 600ml whole milk • 2 Cooks’ Ingredients Marmalade Oranges, zest • Icing sugar, to dust