  Constraining the inflationary epoch is one of the aims of modern cosmology.
In order to fully exploit current and future small-scale observations, it is
necessary to devise tools to directly relate them to the early universes
dynamics. We present here a novel reverse engineer approach able to connect
fundamental late-time observables to consistent inflationary dynamics and,
eventually, to the inflaton potential. Employing this procedure, we are able to
describe which conditions can give rise to a raised plateau in the power
spectrum of curvature perturbations at small scales, which are not constrained
by CMB observations. Within this new phenomenologically-driven approach, we
find that inflation can generate a raised plateau in the spectrum of curvature
perturbations that potentially connects three fundamental observables: a
dominant component of the dark matter in the form of asteroid-mass/atomic-size
primordial black holes; detectable signals in stochastic gravitational waves
and a subdominant fraction of stellar-mass primordial black holes mergers.
