We report on the results of a NuSTAR observation of the Supergiant Fast X-ray Transient pulsar IGR J11215–5952 during the peak of its outburst in June 2017 . IGR J11215–5952 is the only SFXT undergoing strictly periodic outbursts , every 165 days . NuSTAR caught several X-ray flares , spanning a dynamic range of 100 , and detected X-ray pulsations at 187.0 s , consistent with previous measurements . The spectrum from the whole observation is well described by an absorbed power-law ( with a photon index of 1.4 ) modified , above \sim 7 keV , by a cutoff with an e-folding energy of \sim 24 keV . A weak emission line is present at 6.4 keV , consistent with K _ { \alpha } emission from cold iron in the supergiant wind . The time-averaged flux is \sim 1.5 \times 10 ^ { -10 } \mbox { erg cm$ { } ^ { -2 } $ s$ { } ^ { -1 } $ } ( 3-78 keV , corrected for the absorption ) , translating into an average luminosity of about 9 \times 10 ^ { 35 } erg s ^ { -1 } ( 1–100 keV , assuming a distance of 6.5 kpc ) . The NuSTAR observation allowed us to perform the most sensitive search for cyclotron resonant scattering features in the hard X-ray spectrum , resulting in no significant detection in any of the different spectral extractions adopted ( time-averaged , temporally-selected , spin-phase-resolved and intensity-selected spectra ) . The pulse profile showed an evolution with both the energy ( 3-12 keV energy range compared with 12-78 keV band ) and the X-ray flux : a double peaked profile was evident at higher fluxes ( and in both energy bands ) , while a single peaked , sinusoidal profile was present at the lowest intensity state achieved within the NuSTAR observations ( in both energy bands ) . The intensity-selected analysis allowed us to observe an anti-correlation of the pulsed fraction with the X-ray luminosity . The pulse profile evolution can be explained by X-ray photon scattering in the accreting matter above magnetic poles of a neutron star at the quasi-spherical settling accretion stage .