Preheat the oven to 375°F. Prepare a 9×13 inch baking pan by spraying it with cooking spray and set aside.
In a large bowl, whisk together the beaten eggs, flour, evaporated milk, hot sauce, paprika, onion powder, and salt until well combined. Set aside.
In a large skillet, brown the ground beef over medium heat along with the chopped onions until the onions are soft and the meat is browned, which should take about 5-7 minutes.
Next, add the refried beans to the skillet with the ground beef and mix until fully incorporated.
Cut the tortillas into 1-inch wide strips. Layer half of the tortilla strips in the bottom of the prepared baking pan.
Now, arrange half of the green chilies evenly over the tortilla strips, followed by half of the grated cheese.
Repeat the layers with the remaining tortilla strips, green chilies, and cheese.
Pour the egg mixture evenly over the top of the casserole.
Spread the meat and bean mixture over the egg mixture.
Sprinkle the remaining cheese over the top of the casserole.
Cover the casserole with foil and bake in the preheated oven for 45 minutes. Remove the foil for the last 5 minutes of baking.
Finally, serve hot and enjoy this comforting and flavorful Chili Relleno Casserole!