Until now. Award-winning children’s-book illustrator Maurice Sendak, 75, known for his unvarnished treatment of controversial subjects, has just produced a children’s book of the same name. (He also designed the sets for a one-time revival of the opera in Chicago.) Sendak’s unlikely collaborator on both projects is his playwright-friend Tony Kushner, 47, who won the Pulitzer for his searing AIDS drama “Angels in America” and has been an ardent admirer of Sendak’s since he was 4. Kushner was drawn to the project, he writes in his recent book “The Art of Maurice Sendak,” because “I was immediately moved by [‘Brundibar’s’] beauty as a parable of collective action against injustice.”

The appeal for Sendak was more personal. A Brooklyn-born child of Jewish immigrants who left Europe during World War I, Sendak grew up in the shadow of the Holocaust. His mother constantly reminded him of how lucky he was to be alive; “Brundibar” is an attempt to put that guilt to rest. Sendak is making “his own elegy for the children who perished in the camps who were the same age he was,” says Kushner.

Still, “Brundibar” is not a bleak Holocaust tale, and it bears only passing resemblance to Sendak’s dark, beloved works like “Where the Wild Things Are” and “In the Night Kitchen.” A sweet fable in which good triumphs over evil, it uses whimsical, pastel-colored illustrations to tell the story of Pepicek and Aninku, a brother and sister, who go on a journey to buy milk for their sick mother. They arrive in a town with a spired skyline that evokes Prague, and join forces with three talking animals and 300 children. Together they confront the wicked Brundibar (Czech slang for bumblebee) who prevents them from singing for money (“That’s my racket!”). But they drive him out (“Milk for Mommy! Bullies must be defied!”) and succeed in their mission. Sendak’s picture of the children’s return home celebrates religious tolerance: a doctor wearing a yellow Star of David tends to their mother, and a crucifix hangs on the wall.

Sendak, who believes that children intuit the truth, has never shied from revealing it–even when it’s scary. In “Brundibar,” though there is no mention of Hitler or the Holocaust, the title character wears a Napoleonic hat and a fake mustache; his monkey, a stand-in for Goebbels, is Sendak’s invention and not found in the Czech original.

The project posed unforeseen hurdles for the collaborators. Kushner met the challenge of writing a children’s book; out of a translation from the lyrical Czech, he created what the book’s editor called “relentless rhymed verse.” But he had to rewrite the text when he realized it was redundant: Sendak’s pictures were so vivid that they did not require much explication. And Sendak could not settle on the right style until his friend, cartoonist Jules Feiffer, recommended crayons, watercolor pencils and brush pens. The result–a lushly illustrated, snappily told story–is pure magic.