Coconut cream from coconut butter
Coconut cream is a more concentrated version of coconut milk, with more fat but also more coconut solids. Coconut milk won't mix well with additional coconut oil, because without the additional solids the emulsion will be unstable.

If you'd like to make your own coconut cream from scratch, you'll need a coconut. Alternatively, buy it directly, or skim it off rested coconut milk.