Step 1

Preheat the oven to 375°F (191°C). Generously grease a 9×13-inch baking pan or similar size (about 3-quart) casserole dish.

Step 2

Layer the bagel pieces, chopped pepper, tomatoes, and bacon into the dish. Whisk the eggs, milk, cheese, ground mustard, salt, and pepper together in a large bowl. Pour evenly over bagel mixture.

Step 3

Top evenly with pieces of cream cheese and sprinkle with everything bagel seasoning, if using.

Step 4

Bake for 40-50 minutes or until center is set and edges are golden brown. Remove from the oven and allow to cool for 10 minutes before topping with scallions (if using), slicing, and serving.

Step 5

Cover leftover casserole tightly and refrigerate for up to 1 week.