In a large mixing bowl (or the bowl of your stand mixer), whisk together 2 ½ cup (312g) flour, sugar, yeast, and salt.

Add lightly beaten eggs, egg yolk, milk, and vanilla extract and stir until dough is combined.

Add butter, 1 Tablespoon at a time, stirring until butter is completely incorporated before adding the next, and continue mixing until all butter is completely combined.

Gradually add remaining flour, a few tablespoons at a time, until dough begins clinging to itself and pulling away from the side of the bowl when stirring.

Transfer dough to a lightly floured surface and knead by hand (about 10-15 minutes), or use the dough hook attachment on your stand mixer (about 5-10 minutes) until dough is cohesive, smooth and elastic. Dough will be sticky but should not stick to your hands. You may need to add additional flour during this process, especially if kneading by hand, this is fine.

Transfer to a large oiled bowl, cover with plastic wrap and set in a warm spot to rise until puffed (it will increase in size by about 25%, it will not double as many bread doughs do!), about 1-2 hours.

Once dough has puffed, transfer to the refrigerator and let it rest overnight (for at least 12 and up to 24 hours).

Prepare the filling

The next day, before removing the dough from the refrigerator, lightly grease a 9×5” (23x13cm) bread pan with butter and prepare the filling.

In a medium sized, microwave-safe bowl, combine chopped chocolate, butter, and cream. Heat in the microwave for 25 seconds, stir well, and repeat until mixture is smooth.

Add cocoa powder to mixture and stir until smooth and combined.

Add powdered sugar, vanilla extract, and salt and whisk together until completely combined and smooth. Set aside while you roll out your dough. Note that the filling should be a spreadable consistency, similar to peanut butter, in order to easily use it. If yours is particularly warm or liquid, pop it in the fridge so it can become more firm and spreadable.

Assembly

Remove dough from refrigerator and turn out onto a clean, lightly floured surface. Use a rolling pin to roll dough into an 18×12” (46x30cm) rectangle.

Spread chocolate filling evenly over the dough, leaving a ½ inch (1.5cm) perimeter.

Starting at a shorter (12”) end, roll dough into a tight log, pinching the seam at the end. As you roll you may need to gently squish in the ends so it doesn’t become too long. it will

Use a sharp knife to cut the log in half lengthwise.

With the cut-sides facing up, place the two halves beside each other and twist them around one another 4-5 times. It helps to start in the middle and make two twists down and then, from the middle, two twists up.

Carefully transfer to your prepared bread pan (you may need to gently squish the dough from each end to fit).

Cover the bread pan loosely with plastic wrap and let rise until puffy, about 30-60 minutes. Meanwhile, preheat your oven to 350F (175C).

Baking

Once dough is finished rising, transfer to center rack of 350F (175C) preheated oven and bake for 30 minutes. At the 30 minute mark, tent the bread with foil (to prevent over-browning), and return to 350F (175C) oven to bake for another 30-35 minutes. When temped with an instant read thermometer, the center of the bread should be between 185F-190F (85-88C) when finished.

Simple syrup

Several minutes before bread is finished baking (or immediately after baking), prepare your simple syrup. In a small saucepan over low heat, stir together sugar and water until sugar is dissolved. Immediately after the bread finishes baking, use a pastry brush and brush all of the syrup evenly over the top of the bread.

Allow bread to cool in its pan for at least 30 minutes before removing to a cooling rack where it should cool for another hour before enjoying (the warmer the bread is when you cut into it, the more fragile it will be).