MUonE Commissioning and Run--1 First Results

The MUonE experiment aims to determine the leading-order hadronic vacuum polarization contribution to the muon anomaly $a_\mu$ by measuring small-angle $\mu e\!\to\!\mu e$ scattering at 160~GeV. Normalizing the amplitude to the SM QED prediction yields $\Delta\alpha_{\rm had}(t)$, directly linked to $a_\mu^{\rm HVP\text{-}LO}$. In Summer 2025, MUonE collected Run--1 data with a refurbished PbWO$_4$ ECAL integrated with the silicon tracker and muon filter in a single DAQ. We report stable operation with crystal-by-crystal calibration, precise ECAL--tracker synchronization and spatial matching, and monitored energy linearity and noise. We present the first correlated angle--energy distributions consistent with elastic scattering, enabling $e/\mu$ separation and background control. We outline next steps toward physics-quality PID and systematic uncertainties.