Recommendation for a Milkshake place

Hi! Foreign student here. I have been craving for a good milkshake recently but haven't been able to find a definitive place to go to. Would like to have a couple options so I know exactly where to head to before I step out. I don't mind if it's like a dessert/burger/bar/etc place that just happens to sell a milkshake since I prefer places that I can spend a couple hours doing some work.

and yeah, I prefer the heavier ones, the things that would get like a non-existent F on nutri-grade.

Would love to hear all of your recommendations and looking forward to visiting them!