Sift the white flour into a large bowl, add the wholemeal flour and mix it well then add the salt and the nigella seeds. Make a well in the middle and add the whole eggs. Set aside.
Warm up the water in a pan (make it hot but do not boil it. Make it hot enough to melt the butter in it.
In a separate bowl or mug mix the yeast with approximately 1/2 cup of the lukewarm water (take it from the 500ml water just before this gets too hot). Add the sugar and mix until the yeast and the sugar has dissolved completely. Pour this into the well over the eggs.
Going back to the water, when this is fairly hot turn off the heat and add the butter and the milk. Use when the water temperature has dropped and it’s lukewarm. if you’re sold its coarser add the salt here.
Allow the yeast mixture to start bubbling up, this will take approximately 15 minutes and then start kneading. Add the water and the butter all at once (should be lukewarand knead for approximately 10-15 min until your hand will be almost clear of any dough.
Form the dough into a big ball, cover and place in a nice and warm place. Allow it to rise for any time between 45-90 mins. It should be double in size.
When the dough has risen enough, take it out and place onto a lightly floured or oiled work surface. Gently flatten it to get rid of all air bubbles.
Using a knife cut the dough into approx 24 equal portions. If you wish to make perfectly equal buns use a kitchen scale to weigh each portion. I’d start by weighing the entire dough first and then divide by the number of rolls you want to make. You can make mini ones or bigger buns. Your choice here.
Gently flatten each piece like a pancake and then carefully gather the ends and pinch the dough to seal in the center. Flip the dough overwhile in your palm and roll into a ball till you happy with its roundness. Transfer it to the baking sheet and place them at about 1 inch (2.5cm) apart. Cover with a light and clean towel and allow them to rest rest for 30-60 mins. They need to rise again and get nice and puffy. They are now ready to make it to the preheated oven.
Preheat the oven to 195C/ 390F about 15 min before buns are ready to get into the oven. Also place an oven proof dish containing 1 cup of water on the floor of the oven. This will help with creating moisture in the oven so buns remain nice and soft on top.
Just before placing the buns in the oven, beat the remaining egg with a tablespoon of water to make the eggwash. Using a brush, brush the buns when they are done and ready to go into the oven. You may sprinkle some sesame seeds to the top of your rolls if you wish. I have added the seeds to the dough so I have not added any extra on top.
Bake for about 20 minutes or until golden brown. Do the stick test to make sure they are baked to perfection. When ready, transfer the buns to a wire rack and allow to cool completely before cutting them.