Step 1

Position a rack in the middle of the oven and preheat to 400 degrees. Have ready a 9-inch square baking dish.

Step 2

In a blender, combine the salsa verde, crema, cilantro, garlic, and jalapeño or serrano, if using. Blend until combined but not perfectly smooth, about 10 seconds. This is your enchilada sauce. Pour about half of the mixture (about 1 1/3 cups) into a wide bowl; reserve the rest.

Step 3

Heat a 10- to 12-inch well-seasoned cast-iron skillet over medium-high heat. To check whether the skillet is hot enough, sprinkle a drop of water in the center. If it sizzles immediately, it’s ready. Place two or three tortillas — however many will fit — in the skillet, and cook until softened on the bottom, 15 to 30 seconds. Flip and cook until softened on the other side, 15 to 30 seconds more. The tortillas may puff and turn slightly golden, but they should not brown or blacken. Remove from the pan and repeat with the remaining tortillas.

Step 4

Dip one softened tortilla in the enchilada sauce in the wide bowl until lightly coated all over. Arrange approximately 1/4 cup of the chicken in a line down the center of the tortilla, roll it into a cigar-like shape, and transfer to the prepared dish, seam side down. Repeat with the remaining tortillas and chicken, lining the enchiladas in a tight row.

Step 5

Pour the remaining enchilada sauce into the dish, spreading it so it coats each enchilada evenly. (If there is any remaining sauce in the wide bowl, add it to the dish as well.) Sprinkle the cheese over the top and bake for 25 to 30 minutes, or until the sauce is bubbling and the cheese starts to brown. Garnish with cilantro and onion slices, if desired, and serve hot, family-style.