Step 1: Cook the Pasta
Bring a pot of salted water to a boil. Cook elbow macaroni according to package directions until al dente. Drain and set aside.

Step 2: Cook the Beef Mixture
While the pasta cooks, heat a large nonstick skillet over medium heat. Add ground beef, chopped onion, and minced garlic. Cook until the beef is no longer pink, breaking it into crumbles as it cooks. Drain any excess fat.

Step 3: Add Sauce Ingredients
Stir in the diced tomatoes (with juices), kidney beans, tomato paste, chopped green chiles, salt, chili powder, cumin, and pepper. Simmer for 5 minutes to blend flavors.

Step 4: Combine with Macaroni
Add the drained macaroni to the beef mixture. Stir to combine evenly.

Step 5: Assemble and Bake
Preheat oven to 375°F (190°C). Lightly coat a 13×9-inch baking dish with cooking spray. Transfer the chili macaroni mixture into the dish and spread evenly. Cover with foil and bake for 25–30 minutes, until bubbly.

Step 6: Add Cheese Topping
Remove the foil, sprinkle the top with shredded cheese, and bake uncovered for an additional 5–8 minutes, or until the cheese is melted and golden.

Step 7: Garnish and Serve
Optional: Sprinkle with sliced green onions before serving.