Preheat oven to 160 ° C/325F.
Spread the sliced barm brack bread with butter on one sides and cut into triangles.
In a large bowl, whisk the eggs with the sugar, add the cinnamon, cream and milk, and whisk until combined.
Grease a baking dish of approx. 2 litre / 4pints capacity. Deep each slice into the cream mixture and place them in the prepared dish.
Pour the cream mix over the bread mixture. Leave for 10-20 minutes aside until the cream mixture is mostly been absorbed.
Bake for 40-60 minutes or until coloured and no more runny custard.
Remove from the oven.
Serve warm with custard and butterscotch sauce.