Preheat your oven to 375 degrees F. Spray the inside edges of a 9x13 inch casserole dish with nonstick spray and set aside.

Fill a large pot with water and add about 1 tablespoon of salt until it tastes like seawater. Bring to a boil, add the penne, and cook until just al dente. Pull the pasta 1 minute before the package time. Drain and drizzle with a small amount of olive oil to prevent sticking.

Pour the crushed tomatoes directly into the prepared casserole dish. Add the pesto, sugar, dried basil, oregano, garlic powder, salt, black pepper, and red pepper flakes. Stir until fully combined.

Add the drained penne to the casserole dish and stir until every piece is coated in the tomato pesto sauce.

Shred 1 lb of the mozzarella and stir it into the pasta mixture until evenly distributed.

Shred or slice the remaining 1/2 lb of mozzarella and arrange it in an even layer across the top of the casserole.

Bake uncovered at 375 degrees F for 20 minutes, until the cheese is fully melted and the edges are bubbling. For golden brown spots on top, switch to broil for 1 to 2 minutes. Move the rack close to the broiler and watch carefully.

Remove from the oven and let the casserole rest for 3 to 5 minutes before scooping and serving. This helps the cheese set slightly so it holds together.