To make the eggs: Heat butter in a medium sauce pan over medium heat. Once melted and bubbly, add ham. Cook for 1 to 2 minutes, stirring occasionally until barely beginning to brown along the edges. Lower the heat to low, pour in beaten eggs and sprinkle with salt to taste.
Stir the eggs a couple times, as they cook, for about 4 minutes. Once they begin to set, incorporate the grated cheese and let it melt as the eggs finish cooking, 1 or 2 minutes more. Don’t over cook the eggs; turn off the heat while they are still moist.
To make the chipotle crema: Combine the Mexican crema and adobo sauce in a small bowl and mix well. Garnish with chives. Set aside.
To assemble burritos: In a hot comal or skillet set over medium heat, heat the flour tortillas for about 30 seconds to 1 minute per side. Don’t let them toast, just heat thoroughly. Taking one tortilla at a time, spoon in a couple tablespoons of the ham and cheese scrambled eggs, add a couple slices of avocado, and roll. Serve along with the chipotle crema.