My favorite teacher, who likes to teach “outside the box,” took our American studies class on a field trip to the Old Manse, whose most famous resident was Nathaniel Hawthorne.

My favorite teacher, who likes to teach “outside the box,” took our American studies class on a field trip to the Old Manse whose most famous resident was Nathaniel Hawthorne.

In the first sentence, the two subordinate clauses (who likes . . . and whose most famous . . . ) are nonrestrictive (nonessential) and are correctly set off with commas.