We saw these impressive looking baked goodies in the Challans market at a number of different stalls. This was not like the dense (but delicious) texture of a baked New York style cheese cake, but had a very light, fluffy texture somewhere between cake and bread. In fact, the tourteau fromager didn't even taste all that cheesy - so can only presume it contained fresh, high moisture cheese in the mixture. Some of us thought it was a little bland, although it would be nice with jam.
The most interesting feature, the dark black exterior, imparted a slightly blackened and bitter taste but this was pleasant as it was only a thin layer. We can only assume this blackening is achieved with a layer of sugar on the outside and a hot oven temperature.
Definitely one to try when you find an example.