Prepare the dough: In a small bowl, combine the water, yeast, and 1 teaspoon of the sugar, and proof for 5 minutes or until foamy.
In the bowl of a stand mixer fitted with a dough hook attachment, place the flours and salt. Mix briefly to combine the flours, then add the remaining sugar, butter, egg, and the yeast mixture. Mix on medium-low speed for 5 to 7 minutes, until the dough is smooth and well-formed around the hook. It might seem dry at the beginning but should become a smooth, stiff, yet not sticky, dough by the end.
Transfer the dough to a clean work surface and knead to form into a ball and place into a large bowl. If it's sticky, add a bit of flour to your work surface. Cover with plastic wrap and set aside in a warm spot for 1 hour, until the dough has nearly doubled.
Line a large baking sheet with parchment paper. Turn the dough out onto a clean, unfloured work surface and divide into 8 pieces. Form each piece into a ball by rolling on the countertop with a cupped hand. Place onto the baking sheet and flatten into 3-inch disks. Cover with plastic wrap and let rise for 1 hour. They’ll look slightly more puffy, but they’ll still be somewhat flat disks - that’s ok.
Preheat the oven to 375°F.
Uncover and bake 15 to 18 minutes, until the tops are lightly golden brown. At the 13 minute mark, brush with the egg wash, sprinkle with sesame seeds, and return to the oven.
Let cool on a wire rack and serve.