I will talk about the phase separation mechanism of bosonic binary mixtures in spatially-fragmented traps, evidencing the emergence of phases featuring a different degree of mixing. The analysis is initially carried out by means of a semiclassical approach which transparently shows the occurrence of critical phenomena. These predictions are actually corroborated by the study of genuinely quantum indicators, including, but not limited to, the energy levels' structure and the entanglement between the species. The scope of our work goes also beyond the point-like approximation of potential wells, as it comprises a mean field treatment of the problem which aims at ferrying our theoretical previsions towards an actual experimental realization based on Sodium and Potassium.