In a medium saucepan, heat the olive oil over medium heat. Add the minced garlic and cook until fragrant, about 1 minute. Stir in the chipotle chilis in adobo sauce, tomato sauce, chipotle chili powder, ground cumin, and chicken broth. Season with kosher salt and fresh pepper to taste. Allow the sauce to simmer for about 10 minutes, stirring occasionally.
In a large mixing bowl, combine the shredded chicken, diced onion, minced garlic, cilantro, cumin, dried oregano, chipotle chili powder, chicken broth, and tomato sauce. Mix well until all ingredients are evenly distributed. Season with kosher salt to taste.
Preheat your oven to 375°F (190°C) to ensure even baking.
Take a tortilla and spoon about 1/4 cup of the chicken filling into the center. Roll the tortilla tightly, tucking in the sides as you go. Place the rolled enchilada seam-side down in the prepared baking dish. Repeat until all tortillas are filled.
Pour the prepared sauce evenly over the assembled enchiladas, ensuring they are well covered. Sprinkle the shredded cheese generously on top of the sauce.
Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes. After 20 minutes, remove the foil and continue baking for an additional 10-15 minutes, or until the cheese is bubbly and golden.
Once baked, remove the enchiladas from the oven and let them cool for a few minutes. Garnish with chopped scallions or cilantro, and add any optional toppings before serving.