Preheat the oven to 375 degrees F (190 degrees C). Lightly grease an 8-inch square baking pan.
Heat oil in a skillet over medium heat; stir in onion. Cook and stir until the onion has softened and turned translucent, about 5 minutes.
Combine onion with shredded chicken, chili powder, garlic powder, black pepper, seasoned salt, red pepper flakes, and cumin. Stir in 1/2 cup Cheddar cheese and green chiles. Spread in the bottom of the prepared baking pan and top with remaining Cheddar.
Whisk milk and eggs together in a bowl. Stir in crushed pork rinds and pour over top of the casserole.
Bake, uncovered, in the preheated oven until top of casserole is set, about 45 minutes.