It's very rare that I say this but Le Robin Square in Old Montreal is WORTH the 1.5 hour wait! It's a small family-owned business with Robin's mom cooking in the kitchen and her brother braising the pork belly for 5 days. Robin and her sister were very cheerful and accommodating as servers.
Keep in mind that it's a small restaurant. Our group of 6 people had to let smaller groups of 2-3 people pass whenever a single table was available since we had to wait for the big table that seats 5-6 people. We arrived at Le Robin Square a little before 8:30pm and were the last to get seated at 10pm. They do close at 10pm but because it's a family business and they appreciate their customers waiting on line, we were welcomed to continue eating past 11pm. The Mac n Cheese DID run out at around 9pm but Robin recommended their pork belly dish called "The Ultimate Experience" ($34).
I followed her suggestion and got the pork belly, which literally MELTS in your mouth (must be from the 5 days of braising!). The dish comes with two different sauces for dipping: a creamy, thick celery-root puree and a sweet fruit jam made from apricots and pear. I seriously should have asked her for the recipe! The celery puree was my favorite but they were both incredible. (I licked... well, forked, my entire plate clean even after I was done with the pork belly). This was honestly my best meal in Montreal!