Skillet Chili Mac
Heat 1 tbsp oil in a 12-inch skillet over medium heat until shimmering. Add the beef and cook, breaking up the pieces with a wooden spoon, until no longer pink, about 5 minutes. Drain the beef through a fine-mesh strainer, discarding the fat.
Add the remaining 2 tablespoons oil to the skillet and return to medium-high heat until shimmering. Add the onion, bell pepper and 1/2 tsp salt. Cook until the vegetables are softened, about 5 minutes.
Stir in the garlic, chili powder, and cook until fragrant, about 15 seconds. Stir in the macaroni, tomatoes with their juice, tomato puree, water, brown sugar, and drained beef. Cover and bring to a simmer. Reduce the heat to medium-low and continue to simmer, stirring occasionally, until pasta is tender, about 20 minutes.
Season with salt and pepper to taste. Sprinkle with cheese evenly over the top, cover, and let sit off of the heat until the cheese melts, about 3 minutes.