  We search for a $B$ decay mode where one can find a peak for a $D \bar{D}$
bound state predicted in effective theories and in Lattice QCD calculations,
which has also been claimed from some reactions that show an accumulated
strength in $D \bar{D}$ production at threshold. We find a good candidate in
the $B^+\to K^+ \eta\eta$ reaction, by looking at the $\eta\eta$ mass
distribution. The reaction proceeds via a first step in which one has the
$B^+\to D_s^{*+} \bar{D}^0$ reaction followed by $D_s^{*+}$ decay to $D^0 K^+$
and a posterior fusion of $D^0 \bar{D}^0$ to $\eta \eta$, implemented trough a
triangle diagram that allows the $D^0 \bar{D}^0$ to be virtual and produce the
bound state. The choice of $\eta\eta$ to see the peak is based on results of
calculations that find the $\eta\eta$ among the light pseudoscalar channels
with stronger coupling to the $D \bar{D}$ bound state. We find a neat peak
around the predicted mass of that state in the $\eta\eta$ mass distribution,
with an integrated branching ratio for $B^+\to K^+$ ($D\bar{D}$, bound) ;
($D\bar{D}$, bound) $\to \eta \eta$ of the order of $1.5 \times 10^{-4}$, a
large number for hadronic $B$ decays, which should motivate its experimental
search.
