Preheat oven to 400°F. Slice hot dogs on the bias into 1/2" slices.
Combine beef, remaining onion, garlic and jalapenos in a large oven-safe skillet over medium-high heat. Cook, breaking up beef with a spoon, until beef is browned, about 10 minutes. Drain fat from skillet.
Return to the skillet to heat and stir in chili powder, cumin, salt, sugar, tomato sauce and water. Bring to a simmer, reduce heat to medium-low and continue to simmer for 30 minutes, stirring occasionally.
Stir hot dogs into chili mixture and top with cheddar cheese. Bake skillet for 10 to 15 minutes, until the cheese is melted and bubbling. Top with scallions and serve.