Preheat the broiler. Position the oven rack about 6 inches below the broiler element.
Wash the mushrooms if needed, pat dry with paper towels, and slice into thick slices.
Slice the 6 black olives, thinly slice 1/4 green bell pepper, measure 1 oz grated mozzarella, and beat the 2 eggs until well combined. Measure out 1/2 tsp Spike Seasoning and 1/4 tsp dried oregano.
Heat 2 teaspoons of the olive oil in an 8-inch omelet pan over medium-high heat.
Add the sliced mushrooms and sauté, stirring occasionally, until they release their liquid and are lightly browned, about 6 minutes.
Transfer the mushrooms to a cutting board and divide them roughly in half.
Add the remaining 1 teaspoon olive oil to the pan and heat about 45 seconds over medium-high heat. Reduce heat to medium, pour in the beaten eggs, and evenly sprinkle the 1/4 tsp dried oregano and 1/2 tsp Spike Seasoning over the eggs. Let the eggs cook undisturbed until they are about half set (edges set but center still glossy), about 2 minutes.
Sprinkle half the mushrooms, half the sliced green pepper, half the sliced olives, and half the grated mozzarella over the eggs. Then add the remaining mushrooms, peppers, olives, and the rest of the grated mozzarella.
Cover the pan and cook on the stovetop over medium heat 3–4 minutes, until the cheese is softened and the eggs are nearly set.
If your pan is broiler-safe, place it under the broiler and broil until the cheese is fully melted and nicely browned (about 1–2 minutes for a large oven broiler or about 4 minutes in a toaster oven). If the pan is not broiler-safe, transfer the contents to a broiler-safe baking dish or baking sheet and broil as directed.
Remove from the broiler and serve hot.