Preheat oven to 375. Combine eggs, milk, and half and half in a stand mixer or large bowl. Beat until eggs are light and fluffy. (About 30 seconds on low and 1 minute on medium) Add in parsley and garlic powder. Set aside. Grease an 8x8 casserole dish. Place 1 cup (half) of the diced potatoes on the bottom. Place half of the asparagus, onions, and bacon on top of the potatoes. Top with half of the cheese. Repeat layer. Pour the egg mixture over the top. Bake for 50 minutes or until eggs or until knife inserted in the center comes out clean. Remove from the oven and let sit for 5 minutes before cutting.