Well there are various flavoured Bavarian creams, raspberry, strawberry etc. A lot of folks buy the commercial sleeves because apparently it keeps in a filled cake, at room temperature.
It has never been something I liked particularly, there are a lot of donut shops that use it as a filling. To me it has a slightly sour or "on the turn" taste to it, so I don't use it.
You can get a recipe for the regular Bavarian Cream on Ladycake's site. Here is the link: www.ladycakes.com/Recipes/Fillings/Bavarian%20Cream%20Filling.htm
Hugs Squirrelly cakes