Prep: Preheat oven to 400 F degrees. In a small bowl toss together the Parmesan cheese, dried oregano, salt and pepper.
Assemble: Top each tomato slice evenly with the Parmesan cheese mixture. Drizzle with a bit of olive oil, this is optional.
Bake: Bake for about 5 to 10 minutes or until you notice the cheese starts to turn melt and turns golden brown. You can also turn on the broiler for about a minute if you want a bit more color to the cheese.
Garnish and serve: Garnish with parsley and serve.
Keep the leftovers in an airtight container in the fridge for 3-5 days. You can honestly eat your leftovers cold if you'd like to avoid the reheating process!