Slice and add onions to a pot with some butter and a pinch of salt.
Let them get a slight char on the bottom and then deglaze with water.
Repeat the process until they're nice and caramelized.
Add garlic, fresh Rosemary, and thyme.
Toast for about a minute.
Add beef broth and pasta.
Let this come up to a simmer for about 10 minutes until that pasta is cooked through.
Add milk, gruyere, and cheddar.
