Preheat oven to 375 degrees and grease a 9×13 baking dish.
In a skillet, heat olive oil over medium high heat.
Add garlic for 1 minute, then add onion and bell peppers. Cook for about 5 minutes or until soft.
Add black beans and taco seasoning and toss to warm. Remove from heat.
Lay 2 wheat tortillas on the bottom of the greased baking dish. Spread half of the bean mixture, chicken, enchilada sauce, and cheese over top.
Start another layer of tortillas and repeat the layering, finishing with a nice thick layer of shredded cheese.
Cover and bake for 15 minutes, then remove the covering and bake for another 5 minutes or until the cheese is nice and golden.
Let cool and top with chopped green onion.