Lithium phosphorus oxynitride (Lipon) is an amorphous solid-state electrolyte that can completely suppress Li dendrites. The key to its performance is thought to be its homogenous and pore free morphology. To test this, we present a modified thin film battery configuration with a lithium cobalt oxide cathode, a Lipon electrolyte and a top layer with a copper current collector and an artificial Lipon-Lipon interface parallel to the cathode. Upon electrochemical cycling Li metal rapidly deposits at the edge of this Cu current collector and then proceeds to plate along the 2D Lipon-Lipon interface. As the Li is confined to this 2D plane it confirms the ability of Lipon to suppress Li dendrites. It also demonstrates that the homogenous interface free morphology of Lipon is key to its performance.