Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess.  , Combine all the dough ingredients (starting with the lesser amount of water), mixing until everything is moistened. Add more water if necessary to enable the dough to come together. Cover the bowl and let the dough rest for 20 minutes. Then mix and knead it until it's soft and smooth., Place the dough in a lightly greased bowl, cover, and allow the dough to rise for about 1 1/2 to 2 hours, until it's quite puffy., To make the filling: Just before you’re ready to shape the dough, combine the sugar, cinnamon, and flour. Stir in the melted butter and water until evenly incorporated. Set aside., To make the topping: Combine the flour, sugar, cinnamon, and salt until evenly incorporated. Work in the butter until coarse crumbs form. Set aside., Shape the dough into a 9" x 18", 1/4"-thick rectangle. If the dough "fights back," cover the dough and let it rest for 10 minutes to relax the gluten, then stretch it some more., Smear the dough with the filling, coming to within an inch of the edges., Scatter the nuts and raisins atop the filling., Starting with a short end, roll the dough gently into a log, sealing the seam and ends., Using a pair of scissors or a sharp knife, cut the log in half lengthwise (not crosswise) to make two pieces of dough each about 10" long; cut carefully, to prevent too much filling from spilling out., With the exposed filling side up, twist the two pieces into a braid, tucking the ends underneath. Place the twisted loaf into a lightly greased 9” x 5” loaf pan., Brush the loaf with the egg glaze. Mix together the topping ingredients until crumbly and sprinkle it over the loaf., Cover the loaf, and let it rise until it’s very puffy and crowned a good inch over the rim of the pan, 1 1/2 to 2 1/2 hours. Towards the end of the rising time, preheat your oven to 350°F., Bake the bread for 40 to 50 minutes, tenting with aluminum foil during the final 15 to 20 minutes of baking; the loaf should be a deep-golden brown and a digital thermometer into the center of it should register about 195°F., Remove the babka from the oven, and immediately loosen the edges with a heatproof spatula or table knife., Let the babka cool for 10 minutes, then turn it out of the pan onto a rack to cool completely., Slice the babka and serve it at room temperature; or rewarm individual slices briefly in a toaster, if desired., Store any leftovers, well wrapped, at room temperature for several days; freeze for longer storage.