Pre-heat the oven to 375°F.
Scoop the filling into a greased, large 9-inch x 13-inch baking dish or a large oven-proof cast iron skillet or Dutch oven. As an alternative, scoope into smaller individual-sized baking dishes or ramekins.
Spoon the creamy mashed potatoes over the stew, or use a piping bag and pipe the potatoes over the stew.
If potatoes seem too dry to pipe, whip in a little more hot potato water and they will loosen up nicely.
Drizzle the top with a little truffle oil.
Place on a baking sheet (to catch the drippings) and put in the pre-heated oven; bake until bubbly and golden; about 20 - 30 minutes.
Remove from oven, garnish with fresh parsley and serve.