CHEESECAKE BABKA

Steps:

• Dough: In the bowl of a mixer fitted with the dough hook, beat together milk, yeast, flours, eggs, sugar, vanilla, salt, and butter on low speed until well combined. Transfer dough to work surface and form into a 10-by-8-inch rectangle, about 1 inch thick. Wrap in parchment; refrigerate at least 2 hours and up to 1 day.
• Butter Package: Place butter between two pieces of parchment or plastic wrap. Using a rolling pin, gently beat until butter is slightly softened, then roll into a 9-by-7-inch rectangle. Loosely wrap in plastic; refrigerate at least 2 hours.
• On a lightly floured surface, roll out dough to an 18-by-9-inch rectangle with a short side parallel to edge of work surface. Place chilled butter package on top half of dough. Fold bottom half of dough over butter to cover completely and firmly press to adhere butter and dough to one another. Pinch edges to seal. Roll out dough once more to a 24-by-7-inch rectangle. Fold top and bottom of dough toward center until they meet. Fold bottom half up to cover top half, rotate dough package 90 degrees, and roll out dough to a 28-by-7 1/2-inch rectangle. Repeat folding process. Wrap dough in plastic; refrigerate 1 hour or freeze for later use.
• Filling: In the bowl of a mixer fitted with the paddle attachment, beat cream cheese on low speed until softened. Beat in ricotta until just combined (do not overbeat). Add half the egg (reserve remaining half for egg wash), vanilla seeds, lemon zest, confectioners' sugar, and cornstarch; beat until combined. Refrigerate 1 hour.
• Streusel: In a medium bowl, stir together butter and sugar. Mix in flour until large clumps form. Cover; refrigerate 1 hour.
• Spray three 8 1/2-by-4 1/2-inch loaf pans with cooking spray. Roll out dough to a 27-by-9-inch rectangle. Divide into six 13 1/2-by-3-inch rectangles. Transfer filling to a pastry bag and pipe one-sixth of filling in a line down the center of each rectangle, leaving a 1-inch border on all sides. Pull edges of dough up and pinch to enclose filling. Place two filled portions of dough, seam-side down, on work surface to form an X. Working from center of the X, twist ends. Transfer to prepared pan, seam-side down. Repeat process with remaining dough.
• Preheat oven to 350 degrees. Lightly cover pans with a kitchen towel. Let rise in a warm place until almost doubled in size, 2 to 2 1/2 hours. (Dough should just reach edge of pan.) Gently brush dough with egg wash. Break streusel into pebble-sized pieces and gently sprinkle over loaves, dividing equally. Bake until crust is firm and golden brown, 50 minutes to 1 hour. Transfer pans to a wire rack; let cool 10 minutes. Invert loaves onto racks; let cool completely. Lightly dust with confectioners' sugar.