01 -
Preheat your oven to 375°F (190°C). Position the rack in the top third of the oven, which will help brown the cheese and pepperoni nicely. Lightly grease a 9x13-inch baking dish or casserole dish with cooking spray.
02 -
Bring a large pot of water to a boil and add a generous amount of salt (about 1-2 tablespoons). Add the penne pasta and cook for 2 minutes less than the package directions suggest. This undercooking is important as the pasta will continue to cook in the oven. Once the pasta reaches this al dente stage, drain it thoroughly but don't rinse it.
03 -
Return the drained pasta to the empty pot it was cooked in. Add the marinara sauce and approximately one-third of the sliced pepperoni. Stir everything together until the pasta is evenly coated with sauce and the pepperoni is distributed throughout the mixture.
04 -
Pour the pasta mixture into the prepared 9x13-inch baking dish, spreading it out into an even layer. Make sure the pasta is distributed evenly for consistent cooking and serving.
05 -
Sprinkle the shredded mozzarella cheese evenly over the top of the pasta mixture, covering it completely. Arrange the remaining pepperoni slices over the cheese layer, distributing them evenly across the surface. This top layer of pepperoni will become slightly crispy during baking.
06 -
Place the baking dish in the preheated oven, uncovered, and bake for 20 minutes, or until the cheese is melted and the edges are beginning to bubble. The uncovered baking allows the top to develop a nice golden color.
07 -
After the initial baking time, switch the oven to broil setting. Watch carefully as you broil the top for 2-3 minutes, just until the pepperoni begins to crisp and the cheese gets additional browning. Keep a close eye on it during this step to prevent burning.
08 -
Remove the casserole from the oven and let it rest for about 5 minutes before serving. This brief resting period allows the cheese to set slightly and makes serving easier. Portion into squares or scoops and serve hot.