  We study the low-energy electronic structure of heterostructures formed by
one sheet of graphene placed on a monolayer of ${\rm NbSe_2}$. We build a
continuous low-energy effective model that takes into account the presence of a
twist angle between graphene and ${\rm NbSe_2}$, and of spin-orbit coupling and
superconducting pairing in ${\rm NbSe_2}$. We obtain the parameters entering
the continuous model via ab-initio calculations. We show that despite the large
mismatch between the graphene's and ${\rm NbSe_2}$'s lattice constants, due to
the large size of the ${\rm NbSe_2}$'s Fermi pockets, there is a large range of
values of twist angles for which a superconducting pairing can be induced into
the graphene layer. In addition, we show that the superconducting gap induced
into the graphene is extremely robust to an external in-plane magnetic field.
Our results show that the size of the induced superconducting gap, and its
robustness against in-plane magnetic fields, can be significantly tuned by
varying the twist angle.
