Inspired by the iconic babka at Zabar's in New York City, this squishier textured, more savory approach to babka uses Molly Yeh's challah dough. Found in her book, Molly on the Range, the filling is that Southern staple, pimento cheese, because mayonnaise and cheese are a match made in heaven.
When the dough is finished with its first rise, roll it into a 10" x 14" rectangle.
Spread the mayonnaise over it in an even layer, leaving a 1" border untouched along the long edge closest to you. Sprinkle on the cheddar, pimentos, onion, paprika, cayenne, and a sprinkling of salt and pepper.
Starting at the long edge opposite you, roll up the dough to make a long jelly roll and pinch the edges and seam to seal them shut. Use a serrated knife and, starting 1" down the log, cut the roll lengthwise down the center all the way through. Turn the two halves of the log so the opening is facing up (and the filling doesn't fall out). Twist the two pieces around one another. Fold the dough in half, place it in the loaf pan, cover it, and let it rise for 30 minutes.
Preheat the oven to 375°F. Grease a 9" x 5" loaf pan.
Brush the top of the dough with the egg wash. Bake until the top is golden brown and the loaf has an internal temperature of 185°F when measured with a digital thermometer. Begin checking for doneness at 35 minutes.
Remove the babka from the oven and cool it on a rack for 10 minutes. Tilt it out of the pan and return to the rack to cool completely before slicing.
Store any leftovers in the refrigerator, well wrapped, for up to a week.
