In a medium saucepan or saucier, melt the butter over medium heat until gently foaming.
Sprinkle in the all-purpose flour and whisk continuously for 2 to 3 minutes until the roux turns lightly golden-blonde and develops a nutty aroma.
Gradually stream in the warm turkey broth in a slow, steady trickle while whisking vigorously to create a smooth, lump-free emulsion.
Add the fresh herb sprigs (sage, thyme, rosemary), onion powder, garlic powder, black pepper, and Worcestershire sauce.
Bring the gravy to a gentle simmer over medium heat, stirring frequently along the bottom and sides for 5 to 7 minutes until smooth and thickened.
Remove from heat. Discard the herb stems. Stir in the heavy cream and season with sea salt to taste. Serve hot in a gravy boat!