  Atom- and site-resolved experiments with ultracold atoms in optical lattices
provide a powerful platform for the simulation of strongly correlated
materials. In this letter, we present a toolbox for the preparation, control
and site-resolved detection of a tunnel-coupled bilayer degenerate quantum gas.
Using a collisional blockade, we engineer occupation-dependent inter-plane
transport which enables us to circumvent light-assisted pair loss during
imaging and count n=0 to n=3 atoms per site. We obtain the first number- and
site-resolved images of the Mott insulator "wedding cake" structure and observe
the emergence of antiferromagnetic ordering across a magnetic quantum phase
transition. We are further able to employ the bilayer system for spin-resolved
readout of a mixture of two hyperfine states. This work opens the door to
direct detection of entanglement and Kosterlitz-Thouless-type phase dynamics,
as well as studies of coupled planar quantum materials.
