Preheat oven to 180ºC. Prepare a rectangle or oval baking dish.
If using, butter one side of each hot cross bun half and arrange in baking dish.
In a bowl, whisk together sugar and eggs. Whisk in milk, cream, cinnamon, nutmeg, vanilla paste and rum.
Pour custard over the top of hot cross buns. Press down buns and let soak for 10 minutes.
Sprinkle buns with remaining sugar. Bake for 35 minutes until custard is set. Serve warm with ice cream or cream.
Notes
Slightly stale hot cross buns work best for this recipe
I used regular fruit hot cross buns, however brioche buns, or any of the flavour alternatives (e.g. chocolate, fruit free, apple and toffee etc.) would also work well