It's something like a 'Goulash'. Use whatever type of pasta you have on hand.
In a medium Dutch oven, heat oil over medium-high heat. Add beef & onion; cook, stirring occasionally, until browned. Drain; return beef mixture to pan. Chop with potato masher to make the meat into fine smaller pieces.
Add tomato, 1/3 cup water, chili power, cumin, 1 teaspoon salt, and garlic powder; bring to a boil. Reduce heat to medium; cook, stirring occasionally, until thickened - maybe 12 minutes. Remove from pan & set aside.
In the same pan, melt butter over medium heat. Add flour; cook, whisking constantly, 1 minute. Whisk in milk, remaining 1/2 teaspoon salt, and pepper. Bring to a boil over medium-high heat, whisking constantly. Reduce heat to medium-low. Cook, whisking constantly, until thickened, 2 minutes. Remove from heat.
Stir in cheese until melted. Stir in beef mixture and cooked pasta. Serve with green onion, cheese, and chips.