In a large skillet over medium heat, heat the butter until melted and slightly brown. Add the onion, garlic halves, celery and carrot. Cook, stirring often, until fragrant and vegetables are starting to brown slightly, about 10 minutes.
Remove pan from heat. Whisk in the flour. Place the pan back over heat, whisk and cook the flour mixture until it's lightly brown.
Add 1/4 cup of the broth and stir to help deglaze the pan. Remove from heat once more. Whisk in the poultry seasoning.
Next, whisk in the chicken broth 1/4 cup at a time, keeping the mixture smooth as you pour.
Once all the broth has been added, add the chopped fresh herbs and Worchestershire sauce. Heat gravy mixture over medium heat to a simmer, stirring often.
Place fine wire mesh over a medium sized bowl and strain the gravy.
Taste the gravy mixture. Stir in salt, pepper, and more poultry seasoning, if desired. Serve warm.