The Wonderful Wizard of Oz Cookbook, by Monica Bayley. Illustrations by W. W. Denslow. New York: Macmillan Publishing Company. 127 pp. $7.95.

This book for young cooks will delight those who are familiar with the Land of Oz. It is keyed to actual references to food in ''The Wonderful Wizard of Oz, '' by L. Frank Baum, author of the original series of Oz books. Some recipes have the names of characters in the adventure, like ''Toto's Almond Chocolate Bark,'' a no-bake candy.

''Ozmaniacs'' will probably even understand the second key: color. The book is organized in sections, with recipes featuring ingredients of particular colors: Yellow ingredients for ''Winkie Country''; blue for ''Munchkin Country, '' red for ''Quadling Country''; and green for the ''Emerald City.'' While many of the recipes seem palatable and fun to make, the ones found in the green section, such as ''Spinach Salad,'' and ''Soldier With Green Whisker Salad,'' made of avocado, green grapes, zucchini slices, and scallions, make this mother-reviewer wonder if young cooks might not rebel.

Monica Bayley's almost-too-clever book is enhanced by illustrations by the original Oz book illustrator, W. W. Denslow, and undoubtedly will have more appeal to collectors of Oz memorabilia than to the young.