Preheat broiler to HIGH. Place oil in a medium-
size cast-iron skillet, and heat over medium,
swirling to coat. Add onion, and cook, stirring
occasionally, until lightly browned, about 6
minutes. Add garlic and cumin. Cook, stirring
often, until fragrant, 1 to 2 minutes. Reduce heat
to medium-low. Stir in drained tomatoes and salsa.
Simmer over medium-low, stirring often, until
slightly thickened, about 2 minutes.
Remove skillet from heat. Stir in chicken, crema,
tortillas, and 1/2 cup of the Monterey Jack
cheese. Top evenly with remaining 1 1/2 cups
Transfer skillet to preheated oven, and broil
until cheese is lightly browned, 8 to 10 minutes.
Top with avocado, and sprinkle with cilantro