How does one use cocoa butter in cooking?
Cocoa butter has an exceptionally high melting point for a vegan lipid.  

For most baking applications, it probably not ideal; you would be better served with a liquid oil, or if you need something solid but malleable, a hydrogenated vegetable oil product like a vegan margarine.

The main culinary use (in general) is thinning chocolate in creating chocolate coated candies or similar, which makes sense as cocoa butter is one of the primary components in chocolate.  Of course, when it is hardens and is in temper, it is literally as hard as chocolate.

Otherwise, you can fry or saute with it, although it would be easier to do so if you purchase cocoa butter grated as it is normally too hard to scoop at room temperature.

If you melt it (and it will melt just below body temperature), you could bake with it, but you may get a different texture than you expect, as when cool, it is much harder than other typical culinary fats.  You will have to experiment and see what the results are like.

It will be too hard to use with creaming method recipes.