Fry diced bacon until crisp. Remove from grease and set aside.
Place onions in bacon grease. Fry until tender.
Remove and mix with bacon. Place onion and bacon into the cooled pie shell.
In a large bowl, mix cheeses, flour, nutmeg and salt. Place in pie shell.
Beat eggs and heavy cream together. Pour over cheese mixture.
Bake at 325 degrees F for 35-40 minutes or until almost set in center.
Let cool for 10-15 minutes before cutting.