• Adjust rack to middle position (top and middle positions for 8 servings) and preheat oven to 425 degrees. Bring a large pot of salted water to a boil. (TIP: Start with hot tap water for faster boiling.) Wash and dry produce. • Trim and quarter zucchini lengthwise; slice crosswise into 1/4-inch-thick quarter-moons.

• Once water is boiling, add penne to pot. Cook, stirring occasionally, until al dente, 9-11 minutes. Reserve 1 cup pasta cooking water (2 cups for 8 servings), then drain. Keep empty pot handy for Step 4.

• While pasta cooks, heat a drizzle of oil in a large pan over medium-high heat. Add beef*, zucchini, Italian Seasoning, garlic powder, a big pinch of salt, and pepper. • Cook, breaking up meat into pieces, until zucchini is tender and beef is cooked through, 5-7 minutes. (For 8 servings, work in batches, adding a drizzle of oil between batches.) • Remove pan from heat. TIP: If there’s excess grease in your pan, carefully pour it out.

• Transfer beef mixture to pot used for pasta; add marinara, tomato paste, stock concentrates, and 1/2 cup reserved pasta cooking water (1 cup for 8 servings). Bring to a boil over medium-high heat; cook, stirring occasionally, until sauce is slightly thickened, 2-3 minutes. TIP: If sauce is too thick, stir in more reserved pasta cooking water a splash at a time. • Turn off heat; add drained penne to pot with sauce and stir to combine. Taste and season with salt and pepper if needed.

• Transfer pasta to a lightly oiled 9-by-13-inch baking dish (use 2 lightly oiled 9-by-13-inch baking dishes for 8 servings). Carefully dollop ricotta all over pasta and top with mozzarella. • Bake, uncovered, on middle rack until cheese is melted, 10-12 minutes (for 8 servings, bake on top and middle racks, switching rack positions halfway through). • Increase oven temperature to broil; bake until cheese is browned, 2-3 minutes more. TIP: Watch carefully to avoid burning.

• Let baked penne cool for 5 minutes before serving. Sprinkle with as many chili flakes as you like. Serve family style. Ground beef is fully cooked when internal temperature reaches 160°.