- 2½ lb. russet potatoes (about 4)
- 4 tbsp. unsalted butter, softened
- 2 egg yolks, plus 1 egg mixed with 1 tsp. heavy cream, lightly beaten
- ⅛ tsp. freshly grated nutmeg
- Kosher salt and freshly ground black pepper, to taste
1. Heat oven to 400°. Using a fork, prick potatoes all over; place on a baking sheet. Bake until tender, 1½ hours; let cool, then peel and pass through a food mill or ricer.
2. Mix potatoes, butter, yolks, nutmeg, salt, and pepper in a bowl; transfer to a piping bag fitted with a ¾" star tip. On a parchment paper-lined baking sheet, and working in a tight circular motion, pipe twelve 2½" cones about 2" high. Brush with egg mixture; bake until golden brown, 40–45 minutes.