Asparagus Frittata

Name: Asparagus Frittata
Ingredients: 12 large eggs; 1/3 cup whole milk (or half and half for a richer frittata); 1 teaspoon kosher salt (or 3/4 teaspoon fine sea salt); 1/4 teaspoon freshly ground black pepper; 2 green onions (thinly sliced); 1 ounce grated Parmesan cheese (or Pecorino Romano cheese); 1 tablespoon butter; 2 tablespoons avocado oil (or other high heat oil); 12 ounces thin asparagus spears (woody ends snapped off and cut diagonally into 2-inch pieces); 3 ounces shredded mozzarella cheese