  We present the results of a near-infrared imaging study of high redshift
(z~3) quasars using the ESO-VLT. Our targets were selected to have luminosities
among the highest known (absolute magnitude M_B <~ -28. We searched for
resolved structures underlying the bright point-source nuclei by comparing the
QSO images with stars located in the same fields. Two QSOs (HE2348-1444 at
z=2.904 and HE2355-5457 at z=2.933) are clearly resolved in K_S, and with
somewhat lower significance also in H; one object is resolved only in K_S. At
these redshifts, H and K_S correspond almost exactlly to rest-frame B and V,
respectively, with virtually no K-correction. We also report briefly the
non-detection of some additional QSOs. The detected host galaxies are extremely
luminous with M_V ~ -25. Their rest-frame B-V colours, however, are close to
zero in the Vega system, indicating substantial contributions from young stars
and a stellar mass-to-light ratio below 1 (in solar units). Tentatively
converting M_V and B-V into rough estimates of stellar masses, we obtain values
of M_star in the range of several 10^11 M_sun, placing them within the
high-mass range of recent high-redshift galaxy surveys. We present optical
spectra and use CIV line width measurements to predict virial black hole
masses, obtaining typical values of M_bh ~ 5x10^9 M_sun. With respect to the
known correlation between host galaxy luminosity L_V(host) and M_bh, our
measurements reach to higher luminosities and redshifts than previous studies,
but are completely consistent with them. Comparing our objects with the local
(z~0) M_bh - M_bulge relation and taking also the low stellar mass-to-light
ratios into account, we find tentative evidence for an excess in the
M_bh/M_bulge mass ratio at z~3.
