Adjust rack to top position and preheat broiler to 500 degrees). Bring a large pot of salted water to a boil. Slice mozzarella into thin rounds. Pat chicken dry with paper towels, then season all over with salt, pepper, and half the Tuscan Heat Spice (you’ll use the rest later).

Once water is boiling, add penne to pot. Cook until al dente, 9-11 minutes. Reserve 1/4 cup pasta cooking water, then drain.

Meanwhile, heat a large drizzle of oil in a large, high-sided pan over mediumhigh heat (use an ovenproof pan if you have one). Add chicken and cook, stirring occasionally, until browned on all sides but not yet cooked through, 1-2 minutes. (TIP: Don’t overcrowd the pan—you may want to work in batches so the pieces brown evenly.)

Add crushed tomatoes, stock concentrates, penne, remaining Tuscan Heat Spice, and reserved pasta cooking water to pan; stir to combine. Simmer until sauce has thickened slightly, 2-3 minutes. Stir in 1 TBSP butter; season with salt and pepper. (TIP: If your pan isn’t ovenproof, transfer mixture to a 9-by-13-inch baking dish.)

In a small bowl, combine panko, a drizzle of olive oil, and a pinch of salt. Evenly top pasta mixture with mozzarella and panko mixture. Season all over with pepper.

Broil (or bake) pasta until panko is golden brown and sauce is bubbly, 3-5 minutes. (TIP: Keep an eye on dish while broiling.) Cool slightly, then divide between plates and serve.