Preheat oven to 350° and bring a large pot of salted water to a boil.
Once water is boiling, cook pasta shells according to al dente directions on the package. Stir carefully to avoid breaking the shells. When finished cooking, drain the water carefully and set the shells aside.
Meanwhile, pour half of the enchilada sauce into a 13x9 inch casserole dish. In a skillet over medium high heat, heat the olive oil.
When the oil is piping hot, add onion, bell peppers, jalapeño (if using), and garlic. Saute for 3-4 minutes or until everything just begins to soften.
Add black beans, diced chiles, and seasonings. Stir well and cook until the beans are fully heated through. Lightly smash some of the beans and remove them from the heat.
Spoon the black bean mixture into the cooked pasta shells. Place the bottom of each shell into the enchilada sauce. Once all of the shells are filled, pour the remaining enchilada sauce over the top. Sprinkle the shells all over with cheese and bake uncovered for 15-20 minutes.
Top the cooked shells with tomato, green onion, and other toppings of your choice.
Serve and enjoy!