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Testing the standard Shakura-Sunyaev model of accretion is a challenging taskbecause the central region of quasars where accretion takes place is unresolvedwith telescopes. The analysis of microlensing in gravitationally lensed quasarsis one of the few techniques that can test this model, yielding to themeasurement of the size and of temperature profile of the accretion disc. Wepresent spectroscopic observations of the gravitationally lensed broadabsorption line quasar H1413+117, which reveal partial microlensing of thecontinuum emission that appears to originate from two separated regions: amicrolensed region, corresponding to the compact accretion disc; and anon-microlensed region, more extended and contributing to at least 30\% of thetotal UV-continuum flux. Because this extended continuum is occulted by thebroad absorption line clouds, it is not associated with the host galaxy, butrather with light scattered in the neighbourhood of the central engine. Wemeasure the amplitude of microlensing of the compact continuum over therest-frame wavelength range 1000-7000 \AA. Following a Bayesian scheme, weconfront our measurements to microlensing simulations of an accretion disc witha temperature varying as $T \propto R^{-1/\nu}$. We find a most likely sourcehalf-light radius of $R_{1/2} = 0.61 \times 10^{16}\,$cm (i.e., 0.002\,pc) at0.18\,$\mu$m, and a most-likely index of $\nu=0.4$. The standard disc($\nu=4/3$) model is not ruled out by our data, and is found within the 95\%confidence interval associated with our measurements. We demonstrate that, forH1413+117, the existence of an extended continuum in addition to the discemission only has a small impact on the inferred disc parameters, and isunlikely to solve the tension between the microlensing source size and standarddisc sizes, as previously reported in the literature.

Evidence for two spatially separated UV continuum emitting regions in the Cloverleaf broad absorption line quasar