In a large bowl, heat milk until warm - about 30 seconds in the microwave should do. Add the yeast and 1 teaspoon granulated sugar. Whisk together until thoroughly combined and let sit until foamy, about 10 minutes.
Add the remaining granulated sugar and the rest of the dough ingredients (egg through salt) to the milk mixture, stirring everything until it comes together to form a shaggy ball. Then knead the dough by hand (or with a dough hook attachment) until it’s smooth and elastic - this will take about 10 minutes (or less if using a stand mixer). Shape dough into a ball and place in a lightly oiled bowl, cover and let it rise until doubled in size, 1-2 hours.
Make the crumb topping:
Melt the butter in a small bowl. Add the remaining ingredients and stir until well combined. Cover and refrigerate until ready to use.
Make the apricot filling:
In a small sauce pan, combine all the ingredients and bring to a boil. Then reduce heat to medium-low and simmer, stirring occasionally, until the apricots have softened and the liquid has reduced by half, 10-15 minutes.
Remove from heat and allow mixture to cool completely. Then transfer to a food processor and purée until smooth. Set aside.
Make the almond filling:
In a food processor, pulse the almonds and granulated sugar until finely ground.
Add the remaining ingredients and process until the mixture forms a ball. Set aside.
Shape and bake the babka:
Grease a 9"x5" loaf pan.
After the dough has risen, turn it out onto a lightly floured work surface. Roll out dough to a 20"x12" rectangle.
Spread the apricot filling over the dough in an even layer, leaving a 1" border around the edges. Sprinkle the orange zest over the apricot filling, if using.
Spread the almond filling over the apricot filling in an even layer, leaving a 1" border around the edges.
Roll the dough up lengthwise into a long log and pinch seam to seal. Bring the ends together, forming a teardrop-shaped loop, and gently twist a few times. Carefully transfer the twisted dough to the prepared pan.
Cover loaf with a clean kitchen towel and let rise until doubled in size, 1-2 hours.
About 15 minutes before dough has finished rising, preheat oven to 375 degrees.
Brush top of loaf with egg wash and sprinkle crumb topping over the dough, pressing gently so crumbs adhere.
Bake for 50-55 minutes until golden brown.
Remove pan from the oven and let cool for 25 minutes. Then turn out bread onto a wire rack to finish cooling.
Notes
For extra flavor, use a microplane or fine grater to remove the zest from the orange before you juice it. Set aside until ready to shape the babka.
Recipe by Two of a Kind at http://www.twoofakindcooks.com/apricot-and-almond-babka/