Sauté onions in about 3 T. of reserved bacon drippings until translucent. Add flour and another 3 T. bacon drippings and stir to coat. Cook for 3 minutes, until mixture just begins to brown. Create a roux by adding chicken stock slowly, whisking constantly to prevent lumps.

Reduce heat and add potatoes and seasonings. Allow to simmer and thicken ten minutes.

Add half and half and allow soup to heat throughout, but do not boil.

Ladle into bowls and garnish with grated sharp cheddar, bacon, and chives.