For the dough:

1. Place the water into a medium sized saucepan set over medium-low heat. Heat, until the water is lukewarm in temperature. Remove the saucepan from the heat and stir in the yeast until evenly distributed. Set aside to prove, about 5 minutes. Make sure to stir occasionally.
2. Meanwhile, place the flour, sugar and salt in the bowl of a stand mixer fitted with the dough hook attachment. Mix on low speed to evenly combine the dry ingredients. Increase the mixer speed to medium-low then pour in the yeast mixture. Mix to form a rough, shaggy dough, about 4 minutes. Increase the speed to medium and add in the eggs, one at a time, making sure to beat well after each addition. Let the mixer knead the dough until it is smooth, about 3-4 more minutes.
3. Add in the butter, a generous tablespoon at a time, making sure that it is all incorporated before adding in the next tablespoon. Add in the vanilla bean seeds and orange zest. Increase the speed to medium-high and knead the dough until it is smooth, elastic and velvety, about 8 – 10 minutes.
4. Place the dough into a lightly greased bowl then cover it with a layer of plastic wrap. Place the bowl in a warm draft-free area until the dough has risen and is slightly under doubled in size, about 1 1/2 – 2 hours. Knock the dough back and place it in the refrigerator to chill for at least 6 hours, but preferably overnight.

For the filling:

1. The next morning, generously grease a 12 hole muffin pan with neutral oil or butter. Set aside.
2. Remove the chilled dough from the bowl and place it in on a lightly floured surface. Then, using a lightly dusted rolling pin, roll the dough out to form a rectangular shape, about 45 cm x 35 cm (12” x 13”) in diameter.
3. Using a pastry brush, brush the melted butter all over the face of the dough. Then, using a butter knife or offset spatula, spread an even layer of the black tahini over the face of the dough – making sure to leave a 2.5 cm (1”) border around the edges. If your tahini is a little bit runny, give it a gentle stir then place it in the refrigerator to firm up a little bit before spreading. Sprinkle over the finely chopped white chocolate.
4. Starting with the longest side of the dough, begin to very tightly and gently roll the dough until it resembles a log shaped cylinder. Turn the dough log over so that it faces seam side down. Then, use a sharp knife, to slice off 12 evenly sized pieces and place each dough spiral into the muffin pan set aside above. If the cutting is getting messy or the tahini is beginning to run, place the log on a baking tray lined with parchment paper and set it in the freezer to firm up for about 15 minutes.
5. Cover the muffin pan with a layer of plastic wrap and set it aside to rise in a warm draft-free place for 30- 45 minutes, or until the buns are just beginning to double in size. Meanwhile, pre-heat the oven to 180 C (350 F).
6. Once risen, remove the layer of plastic wrap. Lightly glaze the tops of each bun with a thin layer of the egg wash. Bake, for 25-35 minutes, or until the buns are puffed, golden and a skewer inserted into their middle comes out clean. Remove from the oven and set aside to cool for 10 minutes, before carefully taking each bun out of the muffin pan and setting aside on a cooling rack. Immediately glaze them with the orange syrup (recipe follows) and set aside until slightly warm before serving.

For the glaze:

1. While the buns are baking, make the orange syrup. Place the sugar, orange juice and water in a medium sized saucepan set over medium heat. Heat, stirring often to dissolve the sugar, until the mixture comes to a light simmer. Increase the heat to medium-high and let the syrup boil for 2 minutes. Remove the syrup from the heat and stir in the grand marnier. Set aside until needed.