Usually you bake or make a cake (not cook).
Cake can be either countable or uncountable.
I can bake/make a cake. (countable) This sounds like a suggestion or offer to bake/make one cake.
I can bake/make cake. (uncountable) = I know how to do that sort of thing in general. - OR - The person is offering to bake/make an unspecified number of individual cakes. It could be one or it could be several. The meaning depends on the wider context.