A central challenge in turbulence research is understanding the physics underlying the nonlinear interactions between scales of motion. In addition to this multiscale behavior, wall-bounded turbulence supports inhomogeneous structures in the wall-normal direction. We extend the classical spectral (scale-to-scale) turbulence energy cascade, which lacks spatial localization, by introducing the spatiotemporal-spectral (STS) cascade that incorporates wall-normal structure to the spectral description. This spatiotemporal adaptation is energy conserving and suggests very-large-scale-motions provide the architecture to support both wall-normal and spectral energy transfer. In this Letter, we show that despite their energetic dominance, very-large-scale-motions play a passive role in the energy exchange and instead link the inner and outer flow regions through phase synchronization while facilitating energy transfer.