  We propose and analyse a fully-discrete discontinuous Galerkin time-stepping
method for parabolic Hamilton--Jacobi--Bellman equations with Cordes
coefficients. The method is consistent and unconditionally stable on rather
general unstructured meshes and time-partitions. Error bounds are obtained for
both rough and regular solutions, and it is shown that for sufficiently smooth
solutions, the method is arbitrarily high-order with optimal convergence rates
with respect to the mesh size, time-interval length and temporal polynomial
degree, and possibly suboptimal by an order and a half in the spatial
polynomial degree. Numerical experiments on problems with strongly anisotropic
diffusion coefficients and early-time singularities demonstrate the accuracy
and computational efficiency of the method, with exponential convergence rates
under combined $hp$- and $\tau q$-refinement.
