The best steak frites (fries) of my LIFE was at L'imperial Rivoli. Located steps away from the Palace de la Concorde this Parisian gem serves all the best French cuisine. Hubs and I ate here multiple times on our last trip to Paris.
The Louvre is a given, however, buy your tickets in advance here to beat the lines.
Once you have finished your tour at Notre Dame, walk to Berthillon for ice-cream or if you are visiting in the winter order the Chocolate affogato. This is hot chocolate as you have never seen. There is vanilla ice cream melted into the bottom and topped with hazelnut flavored whipped cream.