In a large skillet cook the bacon in over medium-high heat for 5-7 minutes or just until crisp. Remove using a slotted spoon to paper towels to drain.
Reserve 1/3 cup drippings in the skillet. To the skillet add the all purpose flour. Whisking continually add the flour gradually until all of the drippings are absorbed.
Add the milk 1 cup at a time whisking to combine after each addition. Add 5 cups reserving one cup for thinning, if needed. Add salt and black pepper. Mix well.
Bring to a gentle boil, stirring constantly then reduce the heat. Simmer for 5 minutes to reduce slightly and thicken.
Stir half of the bacon into the gravy then serve immediately drizzled over biscuits topped with remaining bacon and chives, if desired.
Notes
You can add a few drops of Kitchen Bouquet Browning sauce to enhance the flavor, if desired.
Thin the gravy further adding additional milk. The gravy will thicken as it cools.
Thicken the gravy further by adding 1-2 Tbsp all purpose flour dissolved in cold milk. Whisk into the gravy to thicken to your taste.