Preheat oven to 300°F. Generously grease a half sheet pan with olive oil or butter, taking special care to get into the creases and corners and up the edges of the pan. Set aside.
Crack all eggs into a large mixing bowl (preferably one with a pouring spout) and whisk lightly. You don't need to have everything perfectly even, but you should have the yolks broken up and partially mixed into the whites.
Add the heavy cream or milk, salt, Italian seasonings, basil, oregano, and pepper and whisk until smooth and even.
Evenly distribute 16 of the pepperoni slices across the bottom of the pan. Scatter the diced cheese over the pepperoni, followed by the green onions. Pour the egg mixture over the pepperoni, cheese, and green onion. Tap the pan on the counter a couple of times to help evenly distribute the egg mixture.
Place pan on the center rack of the preheated oven and bake for 15 minutes, or until the eggs are set and not wet when you touch them.
Remove the pan from the oven and turn the oven to Broil. Scatter the grated cheese evenly over the top and arrange the remaining pepperoni over the cheese. Return the pan to the oven until the cheese is melted and lightly browned in places and the pepperoni is crisp around the edges, about 3 minutes.
Slice into squares and serve with marinara sauce.
This is fantastic, hot, cold or anywhere in between.