  Scattering of ultraintense short laser pulses off relativistic electrons
allows one to generate a large number of X- or $\gamma$-ray photons with the
expense of the spectral width---temporal pulsing of the laser inevitable leads
to considerable spectral broadening. In this Letter, we describe a simple
method to generate optimized laser pulses that compensate the nonlinear
spectrum broadening, and can be thought of as a superposition of two oppositely
linearly chirped pulses delayed with respect to each other. We develop a simple
analytical model that allow us to predict the optimal parameters of such a
two-pulse---the delay, amount of chirp and relative phase---for generation of a
narrowband {\gamma}-ray spectrum. Our predictions are confirmed by numerical
optimization and simulations including 3D effects.
