Mix together the flour, the brown sugar, and the salt in a large bowl. Create a well in the center of the bowl and add the yeast, remaining teaspoon of sugar and ½ cup warm water. Let it stand until nice and foamy, about 5 minutes. 

Gradually mix in the remaining warm water. Dump the sticky mess onto a floured surface and knead the dough until smooth and elastic (about 5-10 minutes by hand, 3-5 minutes if using a stand mixer). Shape the dough into a large ball and place in a bowl slicked with canola oil. Cover with a damp cloth and place in a warm place.  Let rise until the dough has doubled in size, 45-60 minutes. 

Meanwhile, grease the inside of a 3 quart dutch Dutch oven (or an ovenproof saucepan with straight walls, a flat bottom, and a tight-fitting lid) liberally with the butter (4 tablespoons). Sprinkle 1 teaspoon of the nigella seeds on the bottom of the pan. When the dough is ready, divide it into six equal parts and shape into round balls.  Place one ball in the center of the pot and rest all around like petals on a flower. Cover with damp cloth and let it rise once more for 20-30 minutes. 

Preheat oven to 215 degrees. Place the cubes of butter all over the top of the dough and sprinkle with the remaining nigella seeds. Cover tightly with a lid and cook overnight, start checking at 8 hours for a dark golden brown bread, if the bread looks undercooked, continue baking for another hour or so.