Potato Ghosts - cooking recipe

Ingredients

4 lbs large boiling potatoes (preferably white-fleshed)
3/8 cup unsalted butter, cut into pieces
1 1/4 cups whole milk
3 large egg yolks
nigella seeds (to garnish, sometimes mislabeled \"black onion seeds\" or use black sesame seeds)

Preparation

Peel and quarter potatoes, then cover with water in a 4-quart pot and season well with salt. Simmer, partially covered, until tender, 15 to 20 minutes.
While potatoes are simmering, heat butter and milk in a small saucepan until butter is melted. Remove from heat and cover to keep warm.
Preheat oven to 400\u00b0F with rack in middle.
Drain potatoes and force through ricer into a large bowl (or mixer bowl if using stand mixer). Beat in milk mixture, yolks, and 1/2 teaspoon each of salt and pepper with an electric mixer at low speed until combined.
Spread about one-third of potatoes in a buttered 1 1/2-quart shallow ovenproof dish. Transfer remaining potatoes to pastry bag. Pipe potatoes close together into 2 1/2- to 3-inch-high pointed mounds to form \"'ghosts\" and garnish each mound with 2 seeds for \"eyes.\".
Bake until tips of ghosts are golden and potatoes are firm, 20 to 25 minutes.
Cooks' Note: Potatoes can be piped into dish 1 day ahead and chilled, loosely covered with plastic wrap.