01 - Heat olive oil in a large pot or Dutch oven over medium heat. Add the ground beef and cook, breaking it apart with a spoon, until fully browned (about 5 minutes). Drain any excess fat if necessary.
02 - Add the diced onion, minced garlic, and diced bell pepper to the pot. Sauté for 3 to 4 minutes until the vegetables are softened and fragrant.
03 - Stir in the chili powder, ground cumin, smoked paprika, salt, black pepper, and cayenne pepper. Cook for 1 minute to bloom the spices and release their aromas.
04 - Add the tomato paste and cook for 1 minute, stirring constantly. Stir in the diced tomatoes and drained kidney beans until evenly combined.
05 - Pour in the broth and bring the mixture to a gentle simmer, allowing the flavors to meld together.
06 - Stir in the uncooked elbow macaroni. Reduce the heat to low, cover the pot, and cook for 10 to 12 minutes, stirring occasionally, until the pasta is tender and has absorbed the liquid.
07 - Remove from heat and stir in the butter and milk. Add the shredded cheddar cheese and stir continuously until the cheese is completely melted and the sauce is smooth. Adjust seasoning to taste.
08 - Ladle into bowls and serve hot. Garnish with extra shredded cheese or chopped green onions if desired.