1-Roast the 6 to 8 large poblano peppers (about 1 ¾ pounds) by broiling them on a foil-lined baking sheet until their skins blister and blacken. Allow them to rest covered for 15 minutes, then peel off the skins, remove the stems and seeds, and halve the peppers.

2-Preheat the oven to 350 degrees F.

3-In a skillet, cook the 1 pound 90% lean ground beef with the ¾ cup diced yellow onion over medium heat until the beef is crumbled and no longer pink. Drain excess grease, then stir in the 1 teaspoon minced garlic, 1 ½ teaspoons ground cumin, 1 teaspoon salt, ½ teaspoon freshly ground black pepper, and ¼ teaspoon red pepper flakes (if using). Cook for about 1 minute, then remove from heat.

4-In a separate bowl, whisk the 5 large eggs with the 1 ½ cups whole milk, then add the ⅓ cup all-purpose flour and 1 teaspoon baking powder, whisking until mostly smooth.

5-Coat a 9 x 13-inch baking dish with nonstick spray. Layer half of the roasted peppers on the bottom, followed by half of the meat mixture, and then half of the cheese (using ¾ cup of the 1 ½ cups shredded cheddar cheese and ¾ cup of the 1 ½ cups shredded Monterey Jack cheese).

6-Spread the remaining meat mixture over the cheese layer, then add the remaining roasted peppers on top.

7-Sprinkle the remaining cheese (the rest of the 1 ½ cups shredded cheddar cheese and 1 ½ cups shredded Monterey Jack cheese) over the peppers.

8-Slowly pour the egg mixture evenly over all the layers.

9-Cover the dish with aluminum foil and bake for 30 minutes.

10-Remove the foil and bake for an additional 14 to 16 minutes, or until the casserole is puffed and golden brown.

11-Let the casserole rest for 5 minutes before slicing. Garnish with cilantro leaves if desired. Serve with sour cream, salsa, or hot sauce.