Preheat the oven to 425 degrees. Coat a muffin tray with cooking spray.
Chop up the chicken then combine it with the beans/rice, the cotija cheese, most of the green onion, most of the cilantro, juice from 1/2 a lime, the sour cream, and the salsa. Mix until evenly combined, taste then season with sea salt and freshly cracked pepper, to taste.
Using a biscuit cutter (or a ramekin & a knife) to cut out small circles from the large flour tortillas. Carefully place the flour tortilla circles into the muffin tray. Add a spoonful of refried beans into each cup followed by a bigger spoonful of the chicken mixture. Top each cup with a small about of cheddar cheese.
Place into the oven and bake for 15-20 minutes, or until heated through and the tortillas are crisp. Garnish the top with sour cream, avocado, tomato, green onion, and cilantro. Serve with salsa if desired. Enjoy.