Jets are intimately related to the process of star formation, representing the most prominent observational phenomenon during the early protostellar stage. However, little is known about their powering mechanism at the time of their formation, i.e. in embedded (Class0/I) sources, mostly due to the lack of sensitivity and angular resolution at IR wavelengths. We present here the preliminary results of the PROJECT-J (PROtostellar JEt's Cradle Tested with JWST) Cycle 1 program relative to NIRSpec-IFU and MIRI-MRS observations of the Class I protostar HH46 IRS and its outflow. With these observations we aim to obtain a full characterisation of the innermost jet structure and connect it to the wide angle molecular flow impinging on the cavity walls. This will be possible thanks to the large variety of atomic and molecular lines, in the spectral range from 2 to 28 microns, which are the best tracers of the embedded, dense and only moderately excited gas typical of protostars environments.