This French Onion Mac and cheese is from the New York Times. I used the recipe at the link below with the following changes:

• Caramelized the onions traditionally, not with their process. Maybe their way works, but I don’t trust it. I have never found a shortcut that works for carmelizing onions.
• Toasted lightly baguette slices before rubbing with garlic.
• Deglazed the pan with a few glugs of white wine, not 2 Tbsp vinegar.

The dish is exactly as advertised - a supremely decadent macaroni and cheese with a strong caramelized onion flavor. The gruyere is pronounced and only adds to the luxurious taste (and price).

https://cooking.nytimes.com/recipes/1020547-french-onion-macaroni-and-cheese