In a large skillet, melt butter and flour.
Whisk to make a paste.
Cook for 1-2 minutes or until it starts to bubble.
Be careful not to burn.
Slowly whisk in the milk.
Whisk until there are no lumps.
Add salt, garlic powder, cream cheese, and shredded cheese.
With a spatula, gently mix until smooth.
Allow to gently come to boil, whisking frequently, or until slightly thickened.
Add hatch chiles.
Turn heat off.
Garnish with green onions and serve with chips.