Melt the butter in a small skillet over medium heat. When the butter foams, add the garlic and saute until fragrant, about 30 seconds. Add the cream, nutmeg and a good pinch of salt. Bring to a boil and remove from the heat.
Lay the pie crust in a 12-inch cast-iron skillet. Leaving about a 1-inch border of crust uncovered, shingle half the potatoes in circles to cover the crust. Sprinkle with a small pinch of salt and half the cheese. Repeat with the remaining potatoes. Gently fold the edge of the pie crust over the potatoes, pleating it to make a pattern. Brush the crust with the egg wash. Drizzle the cream mixture over the top and sprinkle with the remaining cheese.
Cover and bake for 20 minutes. Uncover and continue to bake until the cheese is browned and bubbly and the crust is golden brown, about another 30 minutes. Let rest for 10 minutes and then slice and serve! Garnish with a pretty herb like Rosemary, FOR DRAMA.