Using a paddle attachment, mix in the softened butter until coarse and crumbly.

In a medium bowl, whisk together 2 eggs and the pumpkin puree until well combined. Set aside.

Using a dough hook attachment, slowly add the yeast mixture to the dry ingredients, followed by the egg and pumpkin mixture. Mix on medium speed for 5-6 minutes (or mix by hand), until the dough becomes smooth and elastic. The dough will be tacky and sticky.

Transfer the dough to a large greased bowl and cover with plastic wrap. Allow the dough to rise in a warm place until doubled in size, about 1 ½ to 2 hours.

Prepare 3 baking sheets with parchment paper and set aside.

Uncover and punch the dough down, then allow it to rest for 5 minutes. Section the dough into 12 pieces and roll into balls. The dough will still be sticky, so you can grease your hands with oil or cooking spray to make it easier to handle, but do not add more flour.

Place 4 dough balls onto each baking sheet, cover with plastic wrap or a kitchen towel, and allow it to rise again for 45 minutes to 1 hour until the dough has doubled in size.

Divide the topping into 12 balls, then lightly flatten each ball in between two sheets of plastic wrap using a tortilla press. You could also use a rolling pin to shape the topping into rounds.

Carefully remove the rolled-out topping from the plastic wrap and drape it onto the risen concha dough. Lightly pat it down to secure the topping onto the dough.

Cut grooves into the topping using a paring knife so it resembles a clamshell, a crisscross pattern, or whichever pattern you prefer.