Start by grabbing your stand mixer. In the bowl, whisk together the flour, sugar, and instant yeast. This trio forms a solid foundation for your dough. Now, add in the eggs, whole milk, and kosher salt. Using the dough hook attachment, mix on low speed for about 2 minutes. You want to see everything start binding together.

It’s time to add the butter. I suggest cutting it into smaller pieces first. Add a few tablespoons of butter at a time, waiting until it’s fully incorporated before you add more. Once all the butter is mixed in, let the mixer run until you have a smooth, elastic dough. Don't worry if it feels a bit sticky; that’s perfectly normal. This should take about 10 minutes.

After kneading, transfer the dough to a large bowl that’s been lightly greased. Make sure to turn the dough so it’s coated in oil. Cover it well with plastic wrap and let it chill in the refrigerator overnight, or at least for 8 hours. This resting time allows the flavors to develop.

While the dough is happily cooling, let’s tackle the filling. In a small saucepan, combine the cubed butter and heavy cream. Set it over medium heat, stirring until the butter melts and the mixture begins to steam. Remove it from the heat and add in the chopped dark chocolate. Stir it all together until smooth. To finish, whisk in the powdered sugar, cocoa powder, and espresso powder. Let this sit until it thickens up a bit—about an hour.

Once your dough is ready, it’s time to bring everything together. Preheat your oven to 350°F (175°C) and prepare two 8x4-inch loaf pans. I recommend greasing the pans with butter and lining them with parchment paper.

On a lightly floured surface, divide the dough in half and return one half to the fridge. Roll the other half into a 12x16-inch rectangle. Spread half of the chocolate filling, taking care to leave a 1-inch border on one side. Starting with the opposite side, roll the dough tightly into a log, pinching the seam to seal it.

Using a large, sharp knife, cut the log in half lengthwise. You'll see those beautiful chocolate swirls! Place the two halves next to each other with the cut sides facing up. Carefully twist them together, keeping the cut sides facing up. Tuck the ends underneath, then place the twist in one of your prepared loaf pans. Repeat this process with the second half of the dough and remaining filling.

Cover the pans loosely with a kitchen towel and let them rise in a warm spot for about 1½ to 2 hours, or until they puff up noticeably. Keep an eye on them; they won’t double in size.

Once risen, pop the pans into your preheated oven. Bake for around 40 minutes or until the tops are golden brown, and a wooden pick inserted into the center comes out clean. The aroma will be nothing short of divine.

While the babkas bake, prepare the syrup. In a small saucepan, combine sugar and water. Bring this mixture to a simmer, stirring to dissolve the sugar completely. Once done, remove it from the heat.

As soon as the babkas come out of the oven, brush them with the syrup. This step adds a lovely sheen while keeping the loaf moist. Let the babkas cool in their pans for about 30 minutes before serving.