A novel complex geometry solar tower molten salt cavity receiver is presented and investigated with regard to its optical and thermal performance. The receiver's design consists of a collector with the goal of limiting the concentrated rays from escaping, which is further enhanced by an absorber design that consists of an array of hexagonal pyramid elements inspired by Garbrecht et al. (2013) that limits re-radiative and convective losses. The performance analysis considers the solar position, DNI and sun shape with an existing heliostat field (PS-10 field) to analyse the receiver, rather than assuming a flux. The optical analysis is conducted with the Monte Carlo ray-tracing approach, while the thermal analysis is conducted using computational fluid dynamics (CFD). The initial design showed impractical receiver efficiencies of 32.8%, while preliminary sensitivity studies on selected parameters increased efficiencies up to 69.9%. In the process a design with improved optics was developed and proposed, with initial results increasing efficiencies up to 82.4%. The study indicates that the design is promising from a heat transfer point of view, although many improvements are still to be made to the design to make it competitive.