Hash Brown Egg Bake

Name: Hash Brown Egg Bake
Ingredients: 1 tablespoon extra virgin olive oil; 1/2 yellow onion (diced); 1 teaspoon garlic (minced); 1 pound ground breakfast sausage; 16 large eggs; 1/2 cup plain Greek yogurt ((5oz)); 1/2 cup milk (regular or plant-based); 1 1/2 teaspoons kosher salt; 1/2 teaspoon ground black pepper; 1 red bell pepper (diced); 2 cups fresh spinach leaves (roughly chopped); 2 cups sharp cheddar cheese (freshly grated (more, if desired)); 20 oz shredded hash browns; optional garnish: chopped green onions and/or sriracha