A fisherman's pie is British comfort food at its most honest — potato, cream, smoked fish, peas, hard-cooked egg — and it does not ask for technique so much as it asks for balance. Ian Winslade, who runs Mission + Market in Atlanta, has cooked in enough fine-dining rooms to know that balance is, in fact, a technique.
His mashed potato topping was piped rather than spread, which creates a ridged surface with more area for browning under the broiler. He used a 2:1 cream-to-butter ratio in the mash, stiffer than a dinner-table mash, so the topping held its peaks during baking rather than slumping into the filling. The filling used hot-smoked fish rather than raw, so no additional moisture released during baking to make the bottom soupy.
Atlanta does not have a fisherman's pier. It has Ian Winslade, which turns out to be sufficient.