Preheat the oven to 350°F, then lightly grease an 8x10" casserole dish.
In a large skillet, warm the olive oil over medium heat. Add the onion and cook for about 3 minutes, until translucent. Next add the bell peppers, jalapeño, corn, chili powder, cumin, and salt then stir and continue to cook for another 5-7 minutes. Remove from heat, stir in the salsa and beans, then set aside.
Layer half of the spiralized sweet potatoes in the bottom of the baking dish then cover with half of the vegetable mixture and top with 1 cup of the cheese. Finish with the remaining sweet potatoes, vegetables and cheese, then cover with foil and bake for 30 minutes.
Remove the foil, set the oven to broil and cook for about 5 more minutes, just until the cheese is lightly browned. Allow to cool for 5-10 minutes, then garnish with diced tomatoes, avocado and cilantro before serving.
If you don't have a spiralizer, you can dice the sweet potatoes into 1-inch cubes instead