Rachel's Jewish Potato Strudel

6 large russet potatoes

3 tablespoons unsalted butter

1 large onion, diced

1 large egg

1 cup ricotta cheese

2 tablespoons minced parsley

2 teaspoons salt, or to taste

1 teaspoon freshly ground black pepper

Pinch of grated nutmeg

12 sheets phyllo dough

½ cup (1 stick) unsalted butter, melted

1 cup sour cream, optional

¼ cup chopped chives, optional

Heat oven to 450 degrees. 
Wash potatoes well and pierce in several places with fork. 
Bake until tender, about 1 hour. Set-aside until cools enough to handle. 
Cut lengthwise in half and scoop out pulp into large bowl. 
Mash pulps with fork or put though a potato ricer.
Melt 3 tablespoons of the butter in large skillet over medium heat. 
Add onion; cook, stirring occasionally, until soft, about 10 minutes. 
Add to potatoes with egg, cheese, parsley, salt, pepper and nutmeg. 
Blend well. Let cool. (Filling can be prepared one day in advance and refrigerated).
Lay 1 sheet of phyllo on work surface with long side facing front. 
Brush with melted butter. 
Lay second sheet on top and brush with melted butter. 
Repeat with 4 more sheets. 
Keep unused phyllo dough covered with wax paper and damp towel at all times.
Shape half of the potato mixture into 2-inch thick log on the phyllo near one side, 
leaving 2-inch border. 
Fold in side of phyllo and roll up strudel. 
Place seam side down on 15-by-11-inch jellyroll pan. 
Repeat with remaining phyllo dough and potato mixture. 
(The strudels may be wrapped in aluminum foil and refrigerated up to 2 days or frozen).

Heat oven to 400 degrees. 
Bake until golden brown, 25 to 30 minutes. 
Let rest 2 to 3 minutes; cut into thick slices with serrated knife. 
Serve garnished with sour cream and chives, if desired.

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