01 - Bring a large pot of salted water to a boil. Cook elbow macaroni according to package directions until al dente. Drain in a colander and set aside.
02 - Heat olive oil in a large skillet or Dutch oven over medium heat. Add the chopped onion and sauté for 3 minutes until softened and translucent.
03 - Stir in the minced garlic and diced red bell pepper. Continue sautéing for 2 minutes until fragrant and the pepper begins to soften.
04 - Add ground beef to the skillet, breaking it apart with a wooden spoon. Cook until evenly browned and no pink remains. Drain any excess fat from the pan.
05 - Sprinkle in chili powder, ground cumin, smoked paprika, salt, and black pepper. Stir continuously for 1 minute to bloom the spices and release their oils.
06 - Add tomato paste, canned diced tomatoes, drained kidney beans, and beef broth. Stir thoroughly to combine all ingredients and bring the mixture to a gentle simmer.
07 - Reduce heat to medium-low and let the chili simmer uncovered for 10 minutes, allowing the flavors to meld and the sauce to thicken.
08 - Fold in the cooked macaroni, milk, shredded cheddar cheese, and half of the mozzarella. Stir until the cheeses are fully melted and everything is evenly coated.
09 - Sprinkle the remaining mozzarella over the top. Cover and let rest off the heat for 2 to 3 minutes until melted, or place under the broiler for a golden bubbly crust.
10 - Serve hot directly from the skillet, garnished with extra cheese or fresh herbs if desired.