Slow-Cooker Chili Mac 'N Cheese

Heat olive oil in a large skillet over medium heat. Add onion, bell pepper, and garlic and cook until softened. Add chili powder, cumin, and cayenne until fragrant, 1 minute. Add ground beef and cook until browned. Transfer beef mixture to slow cooker along with tomatoes, kidney beans and beef broth, and season generously with salt and pepper. Cover and cook on high for 4 to 6 hours or low for 8 to 10 hours. When ready, stir in dry pasta and cook on high for 15 minutes more. When pasta is tender stir in cheeses until evenly distributed and melted. Garnish with scallions and serve.