Preheat your oven to 350°F (175°C). Gather your baking dish and prepare your ingredients.

In a large skillet over medium heat, cook the diced bacon until crispy, about 6–8 minutes. Remove with a slotted spoon, leaving the fat in the skillet. Add sliced onions and sauté until translucent, about 5 minutes.

In a large bowl, combine chopped bagels, crispy bacon, sautéed onions, fresh spinach, diced tomatoes, and cheese. Stir mixture gently and transfer to a prepared baking dish.

Whisk together eggs, milk, and Everything Bagel Seasoning in a separate bowl. Pour over the bagel mixture to moisten evenly.

Cut cream cheese into small chunks and scatter throughout the casserole mixture.

Bake for 45–55 minutes, until edges are golden and center is slightly jiggly.

Let cool for 10–15 minutes before slicing. Enjoy warm, perhaps topped with avocado.