Step 1: Toast the Bagels
Preheat your oven to 350°F (175°C). Spread the torn bagel pieces out on a baking sheet in a single layer. Toast them in the oven for 10–12 minutes until lightly golden and slightly crisp. This helps them absorb the custard later without becoming soggy.

Step 2: Sear the Steak
While the bagels are toasting, heat the olive oil in a skillet over medium-high heat. Season the steak slices with salt, pepper, smoked paprika, garlic powder, and onion powder. Once the skillet is hot, add the steak in a single layer. Sear for 2–3 minutes per side until browned and just cooked through. Remove from heat and set aside.

Step 3: Prepare the Egg Mixture
Crack the eggs into a large mixing bowl. Add the milk, heavy cream, and a pinch of salt and pepper. Whisk thoroughly until well combined. This rich custard will bind the entire casserole together and make it irresistibly creamy.

Step 4: Layer the Casserole
Grease a 9×13-inch baking dish with cooking spray or a bit of butter. Start by layering half of the toasted bagel pieces on the bottom. Sprinkle half of the seared steak over the bagels. Add a mix of both cheeses over the steak. Repeat the layers with the remaining bagel pieces, steak, and cheese.

Step 5: Pour the Custard
Slowly pour the egg mixture evenly over the entire casserole. Use the back of a spoon or spatula to gently press the bagel pieces down, making sure everything is submerged and soaked.

Step 6: Let It Soak
Cover the dish with foil and let it rest for at least 30 minutes at room temperature, or refrigerate overnight if prepping ahead. This soak time allows the bagels to absorb all that rich custard goodness.

Step 7: Bake
Preheat your oven (again, if needed) to 350°F (175°C). Bake the covered casserole for 30 minutes. Then uncover it and bake for an additional 15 minutes until the top is golden brown and bubbly. A knife inserted in the center should come out clean, with no wet egg.

Step 8: Garnish and Serve
Let the casserole rest for 5–10 minutes before slicing. Garnish with sliced green onions for a fresh pop of flavor, and serve warm.