Crock-Pot Breakfast Casserole

In a large skillet over medium heat, cook bacon until crispy, 8 minutes. Drain on a paper towel-lined plate, then chop.  Grease inside of your slow cooker with cooking spray. In a large bowl, whisk together eggs and milk and season with garlic powder, salt, and pepper. In the slow cooker, layer half the hash browns, cooked bacon, onion, and cheese. Repeat layers, then pour over whisked eggs. Cover and cook on low until eggs are fluffy and set, about 6 hours.  Garnish with green onions before serving.