Drain the cooked pasta and place in a large bowl, pour over the bolognese sauce, stir to combine.
Add pepperoni and mozzarella, stir once again and transfer to an ovenproof skillet or cast iron (sprinkle with cooking spray prior).
Sprinkle with more mozzarella cheese on top and layout the whole slices of pepperoni on top and bake for 15 minutes at 350F.
Garnish with dried or fresh oregano and serve immediately!