I can think of two places, but I can't recall the exact names or locations :)
Both are on Nostrand Avenue, one on (I believe) the corner of Dean Street - it's called International Bakery, or something like that. The other is further south, not far from a branch of Gloria's Roti Shop. I've usually passed by there on Sunday mornings and the line literally stretches 10 people out the door.
Another possibility is Conrad's, at 299 Utica Avenue, corner of President, I believe.
Also, most roti shops carry a basic line of desserts. Enjoy, and please report back! I love cassava pones and am always interested in hearing about other places that sell them.