In the bowl of a stand mixer, combine 1 cup flour, granulated sugar, yeast, and salt.

Microwave or in a saucepan over medium heat, warm the milk and the butter until it's lukewarm, about 120 degrees F on an instant-read thermometer. Add the milk mixture to the flour mixture and beat until combined. Add the egg and the vanilla extract and continue to mix until combined.

Attach the dough hook to the stand mixer and gradually add the remaining 2 ¼ cups plus 2 tablespoons flour. Continue to mix and knead on medium speed until all of the flour is incorporated and a sticky dough forms. Add flour 1 tablespoon at a time if necessary.

Spray a large bowl with cooking spray and place dough in the bowl, turning to grease the top. Cover with plastic wrap and let rise in a warm, draft-free area until doubled in size, 45 minutes to 1 hour.

Line a half-sheet baking pan with parchment paper. Set aside.

Lightly punch down the risen dough and let rest for 5 minutes. Turn it out onto a lightly floured surface and divide evenly into 4 portions. Shape into a ball and let sit covered for 15 minutes.

Meanwhile, make the filling: In a saucepan or microwavable bowl, melt the butter. Then combine the sugar, cinnamon, and flour. Add the melted butter, chopped nuts, and raisins; stir until combined. Set aside. If the mixture isn't spreadable by the time you are ready to spread, microwave it for a few seconds to soften.

Roll the Dough: Roll each ball into an 11-inch circle and carefully place it on the prepared pan. Spread ⅓ of the filling onto the dough circle, leaving a ½ inch border. Repeat the process twice. Then roll the final dough ball into an 11-inch circle and place it on top.

Cutting the Dough: Find the center of the dough circle and mark it. I like to use a round 1-inch biscuit cutter for a visual. Using a sharp knife make 16 evenly spaced cuts from the center to the edge of the dough. It's easiest to start with 4 quadrants. Inside of each quarter, you will make three more cuts for a total of 4 wedges in each quarter.

Making the Babka Star: Grasp 1 wedge in each, twist the wedges outward and away from each other twice; then pinch the ends firmly together to make one twisted wedge. Repeat with remaining cut wedges. Cover and let rise in a warm, draft-free place until doubled in size; 30 to 45 minutes. Pinch ends together again if necessary.

Baking the Babka: While the babka is rising for the second time, preheat the oven to 375 degrees F. In a small bowl whisk together 1 egg and 1 tablespoon water. Brush the top of the babka with the egg wash; sprinkle with sugar if desired. Bake until the Babka is golden brown and an instant-read thermometer inserted in the center is at least 190 degrees F; 16 to 22 minutes. Cover with foil to prevent excess browning if necessary. Let cool completely on the pan.