Cook chorizo in a pan on medium heat. Remove and set aside. Place hashbrown patty in the same pan as the chorizo was cooked in and fry the hashbrown in the drippings from the chorizo. When crispy remove and set aside on paper towel to catch grease.
Cook egg to your liking. (This recipe is best with a runny yolk.) Set aside.
Split bolillo roll in half -torta style- and toast on lightly buttered skillet. Remove from heat and brush with guajillo chile sauce.
To assemble, start with bottom half of the bolillo roll, spread crema and then layer, lettuce, hash brown, chorizo, egg, cheese, and top half of the bolillo.
Finish warming the sandwich by toasting, upside down on a skillet. Remove from heat and serve right side up with extra cotija and sauce for dipping.