  We construct a new one-parameter family indexed by $\epsilon$ of two-ended,
spatially-homogeneous black hole interiors solving the
Einstein-Maxwell-Klein-Gordon equations with a (possibly zero) cosmological
constant $\Lambda$ and bifurcating off a Reissner-Nordstr\"om-(dS/AdS) interior
($\epsilon = 0$). For all small $\epsilon \neq 0$, we prove that, although the
black hole is charged, its terminal boundary is an everywhere-spacelike Kasner
singularity foliated by spheres of zero radius $r$.
  Moreover, smaller perturbations (i.e. smaller $|\epsilon|$) are more singular
than larger one, in the sense that the Hawking mass and the curvature blow up
following a power law of the form $r^{-O(\epsilon^{-2})}$ at the singularity
$\{r=0\}$. This unusual property originates from a dynamical phenomenon --
violent nonlinear collapse -- caused by the almost formation of a Cauchy
horizon to the past of the spacelike singularity $\{r=0\}$. This phenomenon was
previously described numerically in the physics literature and referred to as
"the collapse of the Einstein-Rosen bridge".
  While we cover all values of $\Lambda \in \mathbb{R}$, the case $\Lambda< 0$
is of particular significance to the AdS/CFT correspondence. Our result can
also be viewed in general as a first step towards the understanding of the
interior of hairy black holes.
