Substituting canned pumpkin for fresh pumpkin?
As André Soltner is basing his recipe from recollections of growing up in Alsace, it may be that it was not the garden pumpkin, as it's known and which resembles the large US variety most familiar as decoration. 

Several of the many grown in the Alsation region might be better suited to soups and other recipes.

The Hokkaido, similar to Hubbard, has a very hard outer skin, and very dark orange flesh (image courtesy of Wikipedia).



The Muskat-kürbis has bright orange flesh, and is used as a vegetable and for soups, in desserts, as well as being made into jam (image from Kostenlose).



As canned pumpkin is denser, it may give you the result you're looking for in the NYTimes recipe.