In 10-inch skillet, cook sausage over medium-high heat 5 to 7 minutes, stirring occasionally, until no longer pink; drain. Set aside.
In medium bowl, beat eggs, milk and green chiles with whisk. Reserve 3/4 cup of the cheese and 2 tablespoons of the chopped bell pepper for topping.
Line side of 5- to 6-quart slow cooker with foil folded into thirds; spray foil with cooking spray. Place 3 of the tortillas in bottom of slow cooker, tearing if needed to completely cover bottom. Layer with half of the cooked sausage, half of the remaining bell pepper and half of the remaining cheese. Top with 3 more tortillas. Repeat layers of sausage, bell pepper and cheese. Top with remaining 3 tortillas, tearing if needed to cover mixture. Pour egg mixture over tortillas.
Cover; cook on Low heat setting 4 to 5 hours (or High heat setting 2 to 3 hours) or until set and temperature in center is 160°F. Sprinkle with reserved 3/4 cup cheese and 2 tablespoons bell pepper. Cover; cook 5 minutes longer or until cheese is melted. Remove foil before serving by loosening edges with table knife. Serve with salsa.