FLEX-SCALE (Flexible Scalable Energy Efficient Networking) performs disruptive research on optical x-haul network approaches related with Optical Switching Nodes and their Transceiver Interfaces that enable flexible capacity scaling (>10 Tb/s rate per interface, >10 Pb/s capacity per link and >100 Pb/s throughput per optical node), based on utilization of ultra-high bandwidth photonic/plasmonic technologies and the efficient exploitation of optical spatial and spectral switching (UWB/SDM). The network elements will be controlled by a ML-enabled SDN control plane that incorporates new resource allocation algorithms, enabling autonomous programmable disaggregated networks. It will achieve record energy efficiency (sub-pJ per switched/transmitted bit) and low cost, enabled by photonic integration and optical transparency and optimized traffic routing across network layers and segments, thus improving network QoS as required by 6G requirements.