Can i make homemade heavy cream?

I am trying to make whipped cream.. I really need it!!!! I am trying to make a cake.. So i just want to kn ow if i can make heavy cream.. I know this is gonna sound stupid but since it says that whole milk doesn't have enough butter fat can i just add butterx)) sorry i just want to know if i can make homemade heavy cream to make whipped cream?? Thanks:))