Add oil to a large skillet, and heat over medium-high heat. Add sliced onions, and sauté until tender and starting to brown.
Place chicken breasts on top of cooked onions, and pour enchilada sauce on top. Reduce heat to medium, cover, and simmer for 20 minutes, turning chicken over once during cooking.
Meanwhile, heat refried beans in microwave or in another pan on the stovetop.
When chicken is done, remove it from the sauce to shred with two forks. Return meat to the sauce.
Place a layer of chips in the bottom of individual serving bowls. Pour chicken and a generously amount of sauce over the chips in each bowl. The chips should be soaked and softened when served, so don’t skimp on the sauce.
Place a scoop of beans and a dollop of sour cream in the center of each bowl, and crumble cheese evenly over the top. Serve and enjoy!