The purpose of this research was to design a processing route for the conversion of hazardous Municipal Solid Waste (MSW) fly ash into a glass-ceramic material, stable and safe for further industrial, structural, or ornamental applications. The process firstly consists in the transformation of a hazardous MDW fly ash into a vitrous material. Thermal analyses information was used to design the controlled heat treatment that further transformed this vitrous material into an environmentally safe composite. The final product obtained was a glass-ceramic material with randomly oriented crystals embedded in its residual amorphous matrix. The crystalline phases were identified as Nepheline and Diopside. CLSM (Confocal Laser Scanning Microscopy) was used for real-time in-situ observation of the microstructure under simulated heat treatment conditions.