  We propose that a quantum anomalous Hall insulator (QAHI) can be realized in
a nanopatterned two-dimensional electron gas (2DEG) with a small in-plane
magnetic field and a high carrier density. The Berry curvatures originating
from the in-plane magnetic field and Rashba and Dresselhaus spin-orbit
coupling, in combination with a nanoscale honeycomb lattice potential
modulation, lead to topologically nontrivial insulating states in the 2DEG
without Landau levels. In the bulk insulating gaps, the anomalous Hall
conductivity is quantized $-e^{2}/h$, corresponding to a finite Chern number
-1. There exists one gapless chiral edge state on each edge of a finite size
2DEG.
