Cinnamon-Raisin Babka

To prepare dough: Stir milk, yeast, 1/2 teaspoon vanilla and 2 tablespoons granulated sugar in a small bowl or glass measuring cup. Let stand until foamy, about 10 minutes.

Place whole-wheat flour, 2 cups all-purpose flour, salt and the remaining 6 tablespoons sugar in the bowl of a stand mixer fitted with the dough hook. Beat on low speed just until combined. Add 2 eggs, 1/2 cup butter and the yeast mixture; beat on low speed until the dough is starting to come together, 2 to 3 minutes. Increase mixer speed to medium and beat until the dough is smooth and elastic, about 10 more minutes.

Transfer the dough to a bowl lightly coated with cooking spray; cover tightly with plastic wrap. Place in a warm spot, free from drafts, and let rise until doubled in size, about 90 minutes.

Meanwhile, coat two 8-by-4-inch loaf pans with cooking spray and line with parchment paper, allowing 2 inches to extend over the sides of the pans.

To prepare filling: Combine 1 cup brown sugar, melted butter, orange zest, orange juice, cinnamon and vanilla in a medium bowl; stir well. Set aside.

To prepare streusel: Whisk flour, brown sugar and cinnamon in a small bowl. Rub butter into the mixture with your fingers until evenly crumbly. Refrigerate until ready to use.

Once the dough is doubled in size, transfer it to a work surface lightly floured with whole-wheat flour and roll into a 16-by-20-inch rectangle. Spread the filling in a thin even layer over the dough, spreading to the edges. Sprinkle evenly with raisins. Starting with 1 long side, roll up the dough in a tight log. With the log seam-side down, slice it in half lengthwise. Twist both log halves together and then cut the twisted log in half crosswise. Place each half in a prepared loaf pan, tucking ends of dough under if necessary. (If you only have 1 loaf pan, you can wrap the remaining dough half in plastic wrap, and chill until the pan is available.) Cover the pans loosely with plastic wrap and place in a warm spot, free from drafts, until the dough has almost doubled in bulk and leaves an indentation when gently pressed, about 1 hour.

Preheat oven to 350 degrees F. Beat the remaining egg and 1 teaspoon water in a small bowl; brush the top of each babka with the egg wash. Sprinkle the loaves with streusel and bake until golden brown, about 30 minutes. Cool in the pans for 5 minutes. Using the parchment paper as handles, lift the loaves out of the pans and place on wire racks. Serve warm, or cool completely, about 1 hour.