Warm up the milk on the stove or in the microwave. Aim for 100 - 110 degrees F.
Combine milk with active dry yeast and sugar. I like to do this in a liquid measuring cup because it’s easier to handle. Let it sit for 5-10 minutes until it foams.
Pour ingredients from step 2 into a large mixing bowl or the bowl of a stand mixer. Add the butter. Whisk with a stand mixer or hand mixer until the butter breaks down into small pieces. If using a stand mixer, make sure to use the dough attachment.
Add the egg and salt. Whisk until incorporated. Don’t worry if the mixture has small lumps of butter still.
Add the flour a little bit at a time and whisk until a soft dough forms. Knead for 6 minutes. If using a hand mixer, knead with your hands.
Cover with aluminum foil or a kitchen towel and let dough rise in an oiled bowl for 1 hour until it doubles in size.
While your dough is rising, make your filling and prep your loaf pans. Grease 2 loaf pans with butter or neutral oil. Set aside.
Next, pulse your black sesame seeds in a spice grinder or food processor. I would highly recommend a spice grinder. Mix powdered sesame seeds with honey and set aside.
Once your dough is done rising, punch out the air and cut it in half. Working with only half the dough, roll it out into a 9x13 rectangle. Spread the black sesame paste from step 8 on top, leaving 1/2 inch of space between the edge of the paste and the edge of the dough. Tightly roll the dough into a 13 inch log. Use a sharp serrated knife to cut the log in half length wise. Cross one half over the other, cut side down. Tightly twist the two pieces together. Place the finished babka into a prepared loaf pan. Repeat this process for the other half of the dough.
Cover the loaf pans and let the babkas rise for 20 minutes.
Preheat the oven to 350 degrees F (177 degrees C).
Uncover the babkas and bake for 45-50 minutes. When the loaves come out, they should sound hollow when you tap on them.
Cool for 10 minutes before slicing.