In a large skillet, heat the olive oil over medium-high heat. Add the garlic, onion, bell pepper, and corn. Sauté until just softened. Stir in adobo, cumin and black beans.
Add the spinach and sauté until wilted, about 2 minutes. Remove pan from heat. Stir in the optional cilantro and 2 cups of cheese. Set aside.
Preheat oven to 375°F. Lightly spray a 9x13 baking dish with non-stick spray. Pour 0.75 cup of the enchilada sauce into the bottom of the baking dish and spread it into an even layer.
Wrap corn tortillas in a damp paper towel and microwave for 30 seconds, until warmed and pliable.
Then working quickly, spoon about 0.33 cup of the enchilada filling into each tortilla and roll up. Place in the baking dish, seam side down. Continue filling enchiladas and pack the filled tortillas tightly into the baking dish until filled.
Pour remaining enchilada sauce over them, making sure to cover the entire surface. Sprinkle remaining cheese evenly over the enchiladas.
Bake uncovered until hot and bubbly, about 20 minutes. Cool for 5 minutes before serving and garnish with extra cilantro, if desired. Serve hot!