I think the book you are referring to is Traegerflotten by John Baxter. It is totally what-if territory, with Germany somehow having
33 CVs (including Bremen (sistership to Europa) which was wrecked in a bombing raid in March 1941 (which I believe is historically factual)). Of the 32 CVs, 14 were built in France (Atlantikflotte), 12 in Germany and six in Leningrad (Norwegenflotte). 14 are classed as fleet carriers (CV), four as battle carriers (CVB), 10 as light carriers (CVL), and four as auxiliary carriers (ACV).
To give you a flavour as to the context of this book, the French carrier Bearn (renamed Moltke) is the first German carrier. It is mainly used as a training carrier.
The second carrier is the infamous Graf Zeppelin, commissioned 30 July 1940. After sea trials, her catapult sleds and launch rails were removed and replaced with expendable launching bridles and flush decks. As well the 150mm guns were removed, resulting in a weight saving of about 1100 tons. Zeppelin began training her new air group (32 He 100Ts + 6 spares, 24 Ju 87Cs +2 spares) in February 1941. Zeppelin joined Moltke in operations in the Baltic Sea during Operation Barbarossa. Zeppelin resumed operations in the Baltic Sea in March 1942. Presumably, sometime in the summer of 42, the Germans conquered Leningrad and started to put the shipyards there to their use. In September 42 Zeppelin moved with her sister ship Peter Strasser to Trondheim to form the basis of the Norwegenflotte.
