Adjust rack to top position and preheat oven to 425 degrees.

Bring a large pot of salted water to a boil. Wash and dry produce.

Roughly chop spinach.

Once water is boiling, add penne to pot. Cook, stirring occasionally, until almost al dente, 9-11 minutes. (For 8 servings, divide between two large pots or cook in batches.)

Reserve 1 cup pasta cooking water, then drain.

While pasta cooks, coat an 8-by-8-inch baking dish (9-by-13-inch baking dish for 8) with nonstick cooking spray.

Heat pot used for pasta over medium-high heat. Add crushed tomatoes, spinach, stock concentrates, Italian Seasoning, garlic powder, ¼ cup reserved pasta cooking water, and 2 TBSP plain butter (½ cup pasta cooking water and 4 TBSP plain butter for 8 servings). Cook, stirring constantly, until butter is melted and everything is thoroughly combined, 1-2 minutes.

Remove from heat and add drained penne, mozzarella, and Italian cheese blend; stir until everything is coated in sauce. Taste and season with ¼ tsp salt and pepper.

Transfer pasta mixture to prepared baking dish. Coat a large piece of aluminum foil with nonstick cooking spray; cover baking dish with foil, coated side down.

Bake on top rack until sauce is bubbling, 13-15 minutes. TIP: Careful when lifting the foil to check on the penne bake—steam may escape!

Meanwhile, melt garlic herb butter in a medium pan over medium heat. Add panko and cook, stirring constantly, until golden brown, 3-4 minutes.

Transfer garlic herb panko to a small bowl and set aside until ready to serve.

When penne bake is done baking, let cool for 5 minutes.

Top with garlic herb panko, Parmesan, and as many chili flakes as you like. Divide between plates or serve family style directly from baking dish.