Butter the bottom and sides of an 8 1/2x11-inch baking dish with butter.

Use remaining butter to coat 1 side of each bread slice. Place bread butter-side down in the prepared pan until entire bottom is covered in a single layer.

Heat a large skillet over medium-high heat. Cook and stir sausage in the hot skillet until browned, crumbly, and almost fully cooked, about 5 minutes. Sprinkle sausage over bread in an even layer.

Beat eggs, sour cream, and pepper with either a whisk or electric beater. Pour evenly over sausage.

Mix Cheddar cheese and green chiles together in a separate bowl. Sprinkle evenly over the egg mixture. Cover and put in the refrigerator for 8 hours, to overnight.

To bake: Do not preheat the oven. Place, uncovered, in an oven and set to 350 degrees F (175 degrees C). Bake until brown on top, about 1 hour.