Here's a maggi goreng mutton and a mutton dum briyani (weekends special apparently) from Mr Prata (26 Evans Road, #01-02, tel : +65 6235 6993).
To be honest, this place was unexpectedly better than I had in mind. The prices on the whole were generally competitive in comparison to the other "famous prata shacks". Of course with those words being said, I haven't really tried any other prata except for their "Italian" one which featured fillings of cheese, ground mutton, onions and strips of green peppers. It wasn't anything mind blowing at all though.
The dum briyani mutton did come with basmati rice that was rather fragrantly infused with spices that one could just eat them naked. The cooked in meat was on the other hand, a tad too dry even though it wasn't tough. Maggi goreng mutton was competently stir fried with a semi liquid yolk egg. I certainly wouldn't mind coming back again.