Step 1: Sauté the Vegetables for the Filling
Preheat your oven to 375°F (190°C). In a large, oven-safe skillet (a 12-inch cast iron is ideal) or a deep sauté pan, melt 2 tablespoons of butter over medium heat. Add the diced onion and cook for 4-5 minutes until softened. Add the diced jalapeños, red bell pepper, and minced garlic. Cook for another 4-5 minutes until the peppers begin to soften. Stir in the drained green chiles and thawed corn. Cook for 1 more minute, then remove the vegetable mixture to a bowl.

Step 2: Create the Creamy Cheese Sauce
In the same skillet, melt 3 tablespoons of butter over medium heat. Whisk in the flour and cook for 1-2 minutes to form a blonde roux. Gradually whisk in the warm milk and chicken broth until smooth. Whisk in the cumin, chili powder, smoked paprika, and garlic powder. Cook, whisking frequently, until the sauce thickens enough to coat the back of a spoon, about 5-7 minutes. Season with salt and pepper. Remove from heat.

Step 3: Finish the Filling
Take the skillet off the heat. Stir in the shredded Pepper Jack and cheddar cheeses until fully melted and smooth. Stir in the room-temperature sour cream. Add the cooked vegetable mixture and the shredded chicken back to the skillet. Gently fold everything together until the chicken and vegetables are evenly coated in the creamy, cheesy sauce. Taste and adjust seasoning, adding more salt or spice as needed.

Step 4: Prepare the Biscuit Topping
If you are not using an oven-safe skillet, transfer the filling to a greased 9×13 inch (23x33cm) baking dish. Arrange the uncooked biscuit dough rounds evenly over the top of the hot filling, leaving a small space between each biscuit for expansion. You can place them whole, or for better coverage, gently stretch or flatten each biscuit slightly before placing.

Step 5: Apply the Egg Wash and Bake
Brush the top of each biscuit lightly with the beaten egg. Sprinkle the biscuits with everything bagel seasoning or sesame seeds for a beautiful, flavorful finish.

Step 6: Bake to Golden, Bubbling Perfection
Place the skillet or baking dish on a rimmed baking sheet to catch any potential bubble-overs. Bake for 20-25 minutes, or until the biscuits are puffed, deeply golden brown, and cooked through (a toothpick inserted into a biscuit should come out clean), and the filling is bubbling vigorously around the edges.

Step 7: Garnish and Serve
Remove the bake from the oven and let it rest for 5-10 minutes. This allows the filling to thicken slightly. Garnish generously with sliced green onions and fresh cilantro. Serve hot, directly from the skillet or baking dish, with extra sour cream or ranch dressing on the side for dolloping