Artist Duane Bryers is still alive and 101 years old; he did the Hilda series in the '50s and '60s. They look European but he is actually a chubby-chasin' American.
One of Duane Bryers' incredible Hilda paintings done specifically for Bigelow & Brown's Hilda calendars. These were illustrated between 1957 and 1970 although Mr. Bryers continued to do original paintings for the calendars until the early 1980s. These were all primarilly rendered in watercolor employing the service of a number of "plus-size" models, but more often than not, he used only his imagination of "Hilda."
Hilda Does Windows... and window boxes
Hilda by Duane Bryers