Bring to boil and keep at boil until reduced by half (be patient, this takes some time).
Stir in bacon and pasta and simmer until hot; add cheese and 3 teaspoons pasta water. Stir until cheese is melted. Garnish with chopped chives. Serve immediately.
Recipe by Savory Sweet Life at https://savorysweetlife.com/bacon-mac-cheese-with-wisconsin-gruyere/