Question

Can energy be converted into Mass ?

Answer 1

Yes.
But it is not easy as that of mass to energy conversion

Direct mass to energy conversions are still possible through matter-antimatter reactions. But getting energy to be converted into mass will require to have nucllear reaction that absorbs energy and releases a particle. So such 'alchemy' of matter cannot really be implemented.
By using nuclear reactors, we can converte energy into matter