Combine onion and jalapeno, 1/2 teaspoon salt, and oil in a large saucepan. Cover and cook over medium-low heat, stirring often, until the onions and peppers have softened, about 8 to 10 minutes. Stir in the garlic, chili powder, cumin, and sugar, and cook until fragrant, less than 30 seconds. Stir in the tomato sauce, water, and chopped tomato. Raise heat to medium and bring to simmer and cook until slightly thickened, about 5 minutes.

Nestle the chicken into the sauce. Reduce heat to medium-low and cover. Cook until chicken is cooked through (thickest part reaches 160 degrees F), about 15 to 20 minutes. Transfer the chicken to a plate and set aside to cool.

Preheat oven to 425 degrees F.

Strain the sauce through a strainer into a medium bowl, pressing the onion mixture to extract as much liquid as possible. Transfer the onions to a large bowl and set aside. Season sauce with additional salt and pepper to taste.

Shred the chicken into bite-sized pieces. Add to the onion mixture. Then add 1/4 cup of the enchilada sauce, 1 cup cheese, and the cilantro. Toss to combine.

Stack the tortillas on a plate and cover with plastic wrap. Microwave on high for 40 to 60 seconds. Spoon 1/4 cup of the chicken mixture evenly down the center a tortilla. Tightly roll the tortilla and lay seam-side down in a greased 9″ x 13″ baking dish. Repeat with remaining tortillas.

Lightly spray the tops of the enchiladas with cooking spray. Place in oven, uncovered for about 7 minutes, or until the tortillas start to brown slightly.

*Skip this step is you don’t like the crunch*

Reduce heat to 400 degrees F. Remove enchiladas and pour remaining sauce evenly over the top. Sprinkle with remaining cheese. Cover dish with foil (be careful, the baking dish is hot), and bake for an additional 20 minutes until heated through.

Remove foil and bake an additional 5 minutes, until cheese browns. Remove from oven and let stand 10 minutes before serving.