Chez Pierre is a French restaurant in Hillwood, located next to Chez Paris.
It is here in Arnold's Valentine that Ruth was to meet Arnold, where it is revealed that he and Ruth have nothing in common, and while he takes shifts to be with Cecile (his French penpal), who's actually Helga in disguise in Chez Paris, Ruth ends up finding interest in a young waiter who works at Chez Pierre.
In Dinner for Four, Helga won a free coupon for a meal for four at Chez Pierre, she invited Arnold, Gerald, and Phoebe to attend, only to discover when paying the bill that they were in Chez Paris and not Chez Pierre.