Spray the inside of the slow cooker with nonstick cooking spray.
In a skillet, melt the butter over medium heat.
Add the onion and garlic, and cook, stirring until the onion is crisp-tender.
Let cool for about 10 minutes.
Layer half of the frozen hash browns in the slow cooker.
Add half of the onion mixture and half of the mozzarella cheese.
Repeat the layers, ending with the mozzarella cheese.
In a medium bowl, beat the eggs, seasonings, and evaporated milk until blended.
Pour the egg mixture over the ingredients in the slow cooker.
Cover and cook on low for 10–12 hours, or until set.
Sprinkle with Cheddar cheese and parsley, and let stand until the cheese melts.
Serve and enjoy!
Notes / Tips / Wine Advice:
Serving Tip:Serve with a side of fresh fruit or a drizzle of hot sauce for added flavor.Wine Advice:Pair with a light white wine such as Chardonnay or a fresh juice like orange juice to complement the flavors of the casserole.