Potato Chips with Blue Cheese

2 tablespoons unsalted butter 
1 medium onion, finely chopped 
2 tablespoons all-purpose flour 
2 cups milk 
1/2 pound blue cheese such as Maytag Blue, crumbled (2 cups) 
Kosher salt 
1/4 teaspoon cayenne pepper 
One 6-ounce bag thick-cut potato chips 



In a saucepan, melt the butter. Add the onion and cook over 
moderate heat, stirring, about 7 minutes. Whisk in the flour and 
cook for 1 minute. 

Slowly whisk in the milk. Cook over moderate heat, whisking, 
until thickened, 5 minutes. 

Off the heat, whisk in the blue cheese and season with salt 
and cayenne. 

Put half of the potato chips in a large shallow bowl and drizzle 
with half of the blue cheese sauce. Add the remaining chips and 
sauce to make another layer. 

Serve right away.