In a large pot, bring salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente. Drain and set aside.

In a skillet over medium heat, add the ground beef and cook until browned. Drain excess fat.

Add chopped onion and minced garlic to the skillet. Sauté until the onion is translucent.

Stir in the chili powder, cumin, salt, and black pepper. Cook for another minute.

Add the kidney beans and diced tomatoes (with juices) to the skillet. Stir to combine and let simmer for 10 minutes.

Add the cooked macaroni to the chili mixture and stir until well combined.

Serve hot, topped with shredded cheddar cheese, sour cream, and green onions if desired.