In the bowl of a stand mixer fitted with the dough hook, stir together the warm milk, sugar, and yeast on low speed.

Turn off the mixer and let stand until frothy, about 10 minutes.

Add the vanilla, then the flour, salt, nutmeg, and cinnamon. Mix on medium-low speed until the flour is mostly incorporated, about one minute, stopping to scrape down the sides of the bowl as needed.

Add the eggs and mix until the dough forms a ball, about one minute.

Add the butter in a few additions (I usually do a quarter of it at a time) and mix until incorporated, then mix until the dough is smooth and no longer clings to the sides of the bowl, and no butter is visible, about five minutes. Cover the bowl with plastic wrap and let stand in a warm, draft-free place until the dough doubles in size, one to two hours.

Punch down the dough, then cover the bowl and refrigerate for one to two hours, until the dough is firm and cold to the touch. (This will make the dough easier to handle later so you can make perfect twists.)

Meanwhile, prepare the filling. Place the chocolate in a heatproof medium bowl. In a medium saucepan, combine the cream, dulce de leche, corn syrup, cinnamon, and salt and bring to a simmer over medium heat. Cook, stirring frequently, until the dulce de leche fully incorporates into the cream, about three minutes. Pour the warmed cream over the chocolate and stir with a spatula until the chocolate has melted and the mixture is a smooth paste that resembles a loose peanut butter. Your goal is something soft and spreadable that won’t rip the dough; if it’s too loose, add a bit more chocolate and stir to melt and combine. Let cool completely.

Preheat the oven to 350 degrees Fahrenheit. Grease a one-pound loaf pan with cooking spray.

Transfer the chilled dough to a lightly floured work surface and roll it out to a 12-by-six-inch rectangle. Use an offset spatula to spread the filling over the dough in a 1/8-inch-thick layer that extends all the way to the edge. Sprinkle with 1/2 cup (100 grams) of the sugar and the cinnamon. Starting from one long side, roll up the dough into a log.

Using a serrated knife, cut the dough in half lengthwise to create two ropes. Rotate the ropes so the exposed filling faces up, then coil them together tightly without stretching the dough, keeping the filling facing up.

Place the coiled rope of dough in the prepared loaf pan and cover with plastic wrap or a kitchen towel. Let stand until doubled in size, about 20 minutes.

Bake the babka for 45 minutes to one hour, until the dough’s internal temperature reaches 185 degrees Fahrenheit.

Just before the babka finishes baking, in a small saucepan, combine the remaining 1/4 cup (50 grams) sugar and 1/4 cup (60 milliliters) water and bring to a boil, stirring to dissolve the sugar. Remove from the heat and cover the syrup to keep warm until the babka comes out of the oven.

Remove the babka from the oven and immediately brush it with the syrup. Let cool to room temperature before serving. Alternatively, wrap the cooled babka tightly in plastic wrap and freeze for up to one month.