The gas associated with the early stages of star formation contains traces of a large variety of molecular species, many of which are organic in nature. Thanks to last generation (sub-)millimetre interferometers such as ALMA and NOEMA, we are currently witnessing huge progress in our understanding of molecular complexity in star forming regions. In this context, I will introduce our most recent interferometric results in two different objects: (i) the protostellar binary and hot corino source NGC1333 IRAS4A, which is a beautiful example of how the level of chemical richness attained in protostellar cores can vary drastically between neighbouring sources, and (ii) the intriguing protostellar cluster OMC-2 FIR 4, which constitutes so far the best known analogue of the formation environment of the Solar System. The data I will present include ALMA observations and the very first results of the IRAM NOEMA Large Program SOLIS (Seeds Of Life In Space), whose goal is to understand the evolution of organic chemistry across the first phases of formation of solar-mass stars.