Mesoporous superconductors, directed by the self-assembly of block copolymers (BCPs), have shown great potential as quantum metamaterials, exhibiting various novel properties. Traditionally, mesostructured niobium nitride (NbN) is prepared through multi-step furnace treatment process in which niobium oxide (Nb2O5) is converted to NbN. However, this process is time-consuming, often requiring hours, due to the furnace slow heating and cooling rates. Moreover, furnace annealing can often induce internal grain growth, causing the mesoporous structure to collapse. To address this challenge, we have developed an ambient-controlled cell to enable Laser Spike Annealing (LSA) of films in ammonia (NH3) gas. The rapid heating and quenching rates provided by LSA can limit crystal growth and recrystallization during annealing. By using millisecond transient laser heating in an ammonia environment, amorphous mesoporous Nb2O5 thin films were chemically converted to cubic NbN using 30 ms dwell anneals at temperatures above 700 °C. The resulting NbN materials retain their mesoporous structures up to 1300 °C before significant degradation occurs. X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) confirm the formation of NbN with no evidence of crystalline Nb2O5. Similar treatment in air only results in the formation of Nb2O5, suggesting the key role of NH3 in achieving the nitridation. The LSA process streamlines the heat treatment and minimizes damage to the material mesostructure, allowing arbitrary pattern writing. This study demonstrates the versatility of LSA in chemically processing complex mesoporous superconducting quantum materials directed by BCP self-assembly.