  UTe$_2$ is a spin-triplet superconductor candidate for which high quality
samples with long mean free paths have recently become available, enabling
quantum oscillation measurements to probe its Fermi surface and effective
carrier masses. It has recently been reported that UTe$_2$ possesses a 3D Fermi
surface component [Phys. Rev. Lett. 131, 036501 (2023)]. The distinction
between 2D and 3D Fermi surface sections in triplet superconductors can have
important implications regarding the topological properties of the
superconductivity. Here we report the observation of oscillatory components in
the magnetoconductance of UTe$_2$ at high magnetic fields. We find that these
oscillations are well described by quantum interference between quasiparticles
traversing semiclassical trajectories spanning magnetic breakdown networks. Our
observations are consistent with a quasi-2D model of this material's Fermi
surface based on prior dHvA-effect measurements. Our results strongly indicate
that UTe$_2$ -- which exhibits a multitude of complex physical phenomena --
possesses a remarkably simple Fermi surface consisting exclusively of two
quasi-2D cylindrical sections.
