Golden Onion Pie

|The inspiration here is the fantastically rich dish called Zwiebelkuchen (onion cake) a southern German specialty that arrived in America with European settlers and quickly became a staple in Pennsylvania Dutch homes where it is known as Zwiwwelkuche. Slow-cooked onions are combined with eggs and sour cream and spooned into a yeasted dough. The pastry is then partially folded over the filling.|onions|For dough (or use pre-made/store bough short crust pastry):1 1/2 teaspoons active dry yeast80ml warm whole milk (105-115°F)1/4 teaspoon sugar250g all-purpose flour1/2 teaspoon salt1 large egg57g unsalted butter melted and cooledFor filling:680g onions (3-4 large ones) thinly sliced113g bacon finely chopped57g unsalted butter240g sour cream2 large egg yolks |If not using pre-made short crust pastry make the dough:Stir together yeast milk and sugar in bowl of a stand mixer fitted with paddle attachment (or in a bowl to mix by hand) and let stand until foamy about 5 minutes. (If mixture doesn't foam start over with new yeast.)Add flour salt egg and butter and mix at low speed (or stir) until a dough forms. Increase speed to medium-high and beat 3 minutes (or knead by hand 5 minutes).Sprinkle dough lightly with flour and cover bowl with a kitchen towel (not terry cloth). Let dough rise in a draft-free place at warm room temperature until doubled 1 1/2 to 2 hours.Make filling while dough rises:Cook onions and bacon in butter with 1 teaspoon salt and 1/2 teaspoon pepper in a 12-inch heavy skillet covered over medium-high heat stirring occasionally until onions are softened about 20 minutes.Remove lid and cook stirring occasionally until onions are golden 20 to 30 minutes. Cool onions.Whisk together sour cream and yolks then stir into onions.Bake pie:Preheat oven to 375°F with rack in middle.Roll out dough on a lightly floured surface with a lightly floured rolling pin into a 12-inch round. Fit dough into springform pan (stretching slightly if necessary to hang over edge) and spread filling evenly in it. Fold edges of dough over filling leaving some filling exposed in center. Let pie stand 20 minutes at room temperature.Bake until crust is golden-brown and filling is bubbling about 11/4 hours. Cool slightly before serving.|240.00 minutes|6|Epicurious