Chili Mac and Cheese

Name: Chili Mac and Cheese
Ingredients: 1 tablespoon olive oil; 2 cloves garlic, minced; 1 onion, diced; 8 ounces ground beef; 4 cups beef stock; 4 cups water; 2 (14.5-ounce) can diced tomatoes; 1 (15.5-ounce) can white kidney beans, drained and rinsed; 1 (15.5-ounce) can kidney beans, drained and rinsed; 2 teaspoons chili powder; 1 1/2 teaspoon cumin; Kosher salt and freshly ground black pepper, to taste; 10 ounces elbows pasta; 2 cups cheddar cheese, shredded; 2 tablespoons green onions, chopped