Put hot water and cold milk in a bowl and dissolve the yeast in the lukewarm mixture.
Add the egg, melted (or liquid) butter and rice pudding to the bowl.
Mix sugar, salt, cardamom, and flour in a bowl and then add the dry mixture to the bowl with the wet mixture. Stir everything thoroughly with a spoon to make a firm but slightly sticky dough.
Let it rise for 1 hour at room temperature.
Preheat the oven to 225 degrees Celsius (437 degrees Fahrenheit), conventional oven.
Use a spoon to place lumps of dough on a baking tray lined with parchment paper, so you end up with 12 buns.
Put the buns in the hot oven and at the same time place a dish of water in the oven if you wish to bake with steam. Bake the buns for about 18 minutes until they are nice and golden.