Once the dough has proofed, remove the plastic, punch the dough down and let it rest for 5 minutes.
Line 3 large baking sheets with parchment paper.
With clean hands, divide the dough into 12 equal sized portions (about 110 grams each). The dough will feel slightly sticky, add a few drops of oil to your hands to make it easier to work with, but do not add any extra flour to the dough.
Arrange 4 balls of dough on each baking sheet, then brush each portion of dough with the egg wash.
Take a gallon-sized plastic Ziploc bag and cut down the seams so you have two large squares of plastic. Place a portion of the topping in between the plastic squares, then take a plate and gently press down on the topping to flatten it into a circle with a 3.5-4 inch radius. Gently peel off the topping and place it over each portion of concha dough, then use a stencil or knife to score a shell design into the topping. Repeat with the remaining portions of topping dough.
Let the conchas proof one last time for about an hour until doubled in size.
30 minutes before the conchas are done proofing, preheat the oven to 350 degrees F then bake for 20-22 minutes at 350 degrees, until the buns are nice and browned.
Let cool on a wire rack for 30 minutes before serving.