Preheat your oven to 350°F (175°C) and prepare your ingredients: dice the onion, red bell pepper, chop green chiles, shred the cheese, and cut the tortillas into strips.

In a large skillet, heat olive oil over medium-high heat. Add breakfast sausage, cooking for about 4-5 minutes until browned. Add onion and red bell pepper, cooking for another 1-2 minutes until softened, then stir in green chiles.

In a mixing bowl, whisk together the eggs, whole milk, paprika, and red pepper flakes until frothy. Sprinkle in a pinch of salt.

In a lightly oiled baking dish, layer tortilla strips, half the sausage mixture, and some shredded cheese, then pour part of the egg custard. Repeat layering, finishing with tortilla strips and the remaining egg custard.

Bake for about 35 minutes, watching for a slightly jiggly center and a golden-brown top.

Let the casserole rest for 5 minutes before serving, garnishing with chopped chives.