Prepare the pumpkin: Peel the sweet pumpkin and cut it into approximately 2-inch chunks. Set aside.

Make the syrup: In a large pot or Dutch oven, combine the chopped piloncillo (or brown sugar), water, cinnamon sticks, orange zest (if using), and a pinch of salt. Bring the mixture to a boil over medium heat, stirring occasionally until the piloncillo fully dissolves. Reduce the heat and let it simmer gently for 5-7 minutes to allow the flavors to meld.

Simmer the pumpkin: Carefully add the prepared pumpkin chunks to the simmering syrup. Arrange them in a single layer if possible. Ensure the pumpkin is mostly submerged in the liquid; if not, add a little more water until it is. Bring the mixture back to a gentle simmer, then cover the pot and cook for 30-45 minutes, or until the pumpkin is tender, translucent, and has absorbed the delicious syrup. Stir very gently once or twice to prevent sticking.

Reduce the sauce: Remove the lid from the pot and continue to simmer the pumpkin for another 10-15 minutes. This step allows the syrup to thicken slightly and beautifully glaze the pumpkin pieces.

Serve: Remove the pot from the heat and let the Calabaza en Tacha cool slightly before serving. It can be enjoyed warm or at room temperature. Garnish with a drizzle of milk or a dollop of crema Mexicana, if desired.