For roasting the poblano pepper

1. Prep oven. Heat the oven to 475 degrees F.
2. Prep pepper. Split the pepper in half lengthwise so it will lay relatively flat. Remove the stems, seeds, and ribs. Place the pepper halves in a foil lined rimmed baking sheet skin side up.
3. Roast pepper. Bake until the skin is blistered over most of the surface, 15-25 minutes. Remove the pepper from the oven and carefully fold the edges of the foil to wrap the pepper up. Let sit for 15 minutes.
4. Peel pepper. When cool enough to handle, peel away the skin and discard. Coarsely chop the pepper and set aside.

For the sauce

1.  Make sauce. Melt the butter in a medium saucepan. Stir in the chopped poblano pepper. Add in the flour and cook, stirring constantly, for 2 minutes. Whisk in the broth and garlic powder. Let cook over medium heat, stirring frequently, until the mixture bubbles and thickens.
2. Finish sauce. Remove from the heat and stir in the sour cream and cilantro. Season with salt and pepper to taste. Set aside.

For the filling

1. Prep veggies. Drain all the water from the spinach, artichokes, broccoli, and chilis. Be sure to really squeeze all the water out of the vegetables. Roughly chop the artichokes. Set vegetables aside.
2. Make sauce for filling. In a large saucepan, melt butter over medium-high heat. Add the onions and cook, stirring, until soft, 3 to 4 minutes. Add the garlic and cook, stirring, for 45 seconds. Add the flour and cook, stirring constantly, for 2 minutes. Whisk in the milk, and cook, stirring frequently, until thickened. Stir in salt, black pepper, and cayenne pepper.
3. Add veggies. Then add the spinach, artichokes, and broccoli. Stir to combine. Cook until everything is heated through. Adjust the seasoning, to taste.

For assembly

1. Prep oven and pan. Heat oven to 400 degrees F. Spray a 9×13 inch or a 7×11 inch baking dish with non-stick cooking spray (see Notes).
2. Prep tortillas. Warm tortillas in microwave for 60-90 seconds so they are soft enough to roll.
3. Roll enchiladas. Place about 1/3 cup of the filling mixture in a line down the center of a tortilla. Roll up tightly and place in the prepared baking dish, seam-side down. Repeat with the remaining filling and tortillas.
4. Add sauce. Pour the poblano sauce over the top of the enchiladas. Press down on the tortillas slightly with a rubber spatula so that some of the sauce seeps into the enchiladas. Sprinkle enchiladas with cheese.
5. Bake. Bake until sauce is bubbling and slightly golden on top, about 20-25 minutes. Sprinkle with additional cilantro and serve.