When you encrust something, you coat it with a layer of some other material. You might encrust your homemade cheesecake bites in crushed cookie crumbs, for example.
There are many ways to encrust various kinds of food, as when you encrust fish or chicken in breadcrumbs before baking it. A jeweler might encrust a ring in tiny diamonds, and the ocean's tide can encrust a dock with tiny snails or barnacles. The Latin root of encrust is incrustare, which, fittingly, means "to cover with crust."