Stir together flour, sugar, and yeast in a bowl of a stand mixer. Add eggs and 1/2 cup water, mixing with the dough hook until it comes together; this will take a couple minutes.If it doesn’t come together at all, add extra water, 1 tbsp at a time until the dough forms a mass.

Keep the mixer on low, add the salt, then the butter, a spoonful at a time, mixing until it’s incorporated into the dough. Keep mixing on medium speed for 10 minutes until dough is completely smooth; The dough will pull away from the sides of the bowl. If not, you can add 1-2 tbsp extra flour to help it along.

Grease a large bowl with oil and place dough inside, cover with plastic and refrigerate. Leave in the fridge overnight.

Place chocolate and butter in a medium bowl, melt together in 30-second intervals until smooth.

Stir in powdered sugar, cocoa powder, and vegetable oil, keep stirring until smooth and spreadable.

Line 2 9X4 inch loaf pans with parchment paper.

Work with half dough each time, leaving the other half in the fridge to chill. Roll out on a floured surface to about a 10-inch width and as long in length, as you can when rolling it thin, about 10 to 12 inches.

Spread half the chocolate filling on the rolled dough, leaving about 1/2 inch margins. Brush the far away edges of the dough with water. Roll the dough into a tight log, tightening the edges into the log. Transfer the log to a lightly floured baking tray and place in the freezer for 15 minutes this will make it easier to cut in half. Repeat with second dough.

Trim the last 1/2-inch off each end of <g class="gr_ gr_269 gr-alert gr_gramm gr_inline_cards gr_run_anim Grammar only-ins doubleReplace replaceWithoutSep" id="269" data-gr-id="269">log</g>. Cut the log in half lengthwise and place each half next to the other on a flat surface, cut sides up. Pinch the top ends gently together. Lift one side over the next, making a twist while trying to keep the cut sides facing up. Transfer the twist into the prepared loaf pan.

Cover with a damp towel and let the dough rise for another hour at room temperature. Repeat process with the second loaf.

Pre-heat oven to 375°F/190°C. Place loaves on the middle rack of the oven. Bake for 30 minutes, a tester inserted into babka should come out easily and cleanly.

While baking, make the syrup. Boil water, and pour over sugar, stir until sugar dissolves. As soon as the babkas are baked, brush the syrup all over each. Let cool for about 10 minutes in <g class="gr_ gr_268 gr-alert gr_gramm gr_inline_cards gr_run_anim Grammar only-ins doubleReplace replaceWithoutSep" id="268" data-gr-id="268">pan</g>, then transfer to a cooling rack to cool completely before eating.