Diffractive optical elements (DOEs) such as spatial light modulators (SLMs), binary phase gratings, microelectromechanical systems (MEMS) and metasurfaces, have matured to the extent that they can reshape the scattered wavefront, i.e., altering the phase, amplitude and polarization of light. Metasurfaces — flat optic elements composed of subwavelength-spaced array of scatterers with spatially varying geometric parameters such as shape, size, orientation —are among the recent tools that can mould optical wavefronts into arbitrary shapes, point-by-point, with subwavelength resolution. Owing to the recent advances in nanofabrication, multi-layer metasurfaces have now become feasible. Here, we explore the possibilities offered by bilayer metasurfaces and show how it can overcome some of the intrinsic limitations of the widely adopted single layer metasurfaces.