1 1/2 C, Warm milk (110º F)
2 envelopes (1/4ounce each) active dry yeast
1 3/4 C plus a pinch of sugar
3 whole large eggs, plus 2 large egg yolks, room temp.
6 C. all-purpose flour, plus more for dusting
1 t. salt
3 1/2 sticks (1 3/4 C.) unsalted butter, cut into 1-inch pieces, room temp., plus more for bowl and pans
2 pounds semisweet chocolate, very finely chopped
1 T. plus 1 tsp. ground cinnamon
1 T. heavy cream
Streusel Topping (recipe follows)
In a small bowl, sprinkle yeast and a pinch of sugar over the warm milk; stir until disolved. Let stand until foamy, about 5 minutes. In a medium bowl, whisk together 3/4 C. sugar, 2 eggs, and the yolks; add yeast mixture, and whisk to combine.
In the bowl of an electric mixer fitted with the paddle attachment, combine flour and salt. Add the egg mixture, and beat on low speed until almost all the flour is incorporated, about 30 seconds. Switch to dough hook. Add 2 sticks of butter, and beat until completely incorporated and a smooth, soft dough forms, about 10 minutes. The dough should still be slightly sticky when squeezed.
Turn out dough onto a lightly floured work surface, and knead a few times until smooth. Place dough in a well-buttered bowl, and turn to coat with butter. Cover tightly with plastic wrap. Let rise in a warm place until doubled in bulk, about 1 hour.
In a bowl, stir together chocolate, remaining cup of sugar, and the cinnamon. Using a pastry blender, cut in remaining 1 1/2 sticks of butter until combined; set aside filling.
Generously butter three 9-by-5-by-2 3/4-inch loaf pans and line with parchment paper, leaving a 1 1/2-inch overhang along the long sides. Brush more butter over parchment, and set aside. Punch down the dough, and transfer to a clean work surface. Let the dough rest for 5 minutes.
Meanwhile, beat the remaining egg with cream. Cut dough into 3 equal pieces. On a well-floured surface, roll out one piece of dough to a 16-inch square, about 1/8-inch thick. (keep other pieces covered with plastic wrap while you work.) Brush edges of dough with egg wash. Crumble one-third of the chocolate filling evenly over dough, leaving about a 1/2-inch border on the long the sides. Roll up dough lengthwise into a tight log, pinching ends together to seal. Twist dough evenly down the length of the log, a full 5-6 times. Brush the top of the log with egg wash. Crumble 2 T. filling down the center of the log, being careful not to let mixture slide off. Fold log in half into a horseshoe shape, then cross the right half over the left. Pinch ends together to seal and form a tight figure eight. Twist 2 more times, and fit into prepared pan. Repeat with remaining dough and filling.
Preheat overn to 350ºF, with a rack in the lower third. Brush the top of each loaf with egg wash; spronkle 1/3 of the Struesel Topping. Loosely cover each pan with plastic wrap, and let rise in a warm place until dough has expanded and feels pillowy, about 40 minutes.
Bake loaves, rotating halfway through, until golden, about 55 minutes. Reduce oven temp. to 325ºF; bake until loaves are deep golden, 20 to 30 minutes more. (If the tops begin to brown too quickly, tent with aluminum foil.) Transfer pans to wire racks to cool completely. Babkas can be wrapped in plastic and kept at room temp. for up to 3 days.
(makes enough for 3 loaves)
1 2/3 C. confectioners' sugar
1 1/3 C. all-purpose flour
1 1/2 sticks unsalted butter, room temp.
Combine sugar and flour in a large bowl. Unsing a pastry blender, cut in butter until mixture resembles coarse crumbs with some large clumps remaining.