Heat olive oil in a large skillet over medium-high heat. Add onion and saute until translucent, about 5 minutes. Stir in garlic and saute 1-2 minutes longer.
Add chicken, chili powder, cumin, and salt, and stir fry until chicken is cooked through. Stir in beans and tomatoes. Bring to a simmer.
Lay an even layer of chips in the bottom of a 8″ square baking dish (for one large serving to share) or four individual oven-safe bowls. Spread a layer of the chicken mixture evenly over chips, and top with a sparse layer of cheese (I like just enough to hold it all together). Repeat chip/chicken/cheese layer two more times.
Place bowls or baking dish in oven for about 5 minutes, just until cheese is melted. Top with additional desired toppings, and dig in!