Pat chops dry and season with 1/2 teaspoon salt and pepper. Dust lightly with 2 tablespoons flour, shake off excess and discard any loose dredging flour that contacted raw pork.
Heat oil in a large skillet and sear chops for 3 minutes per side until lightly browned; transfer to a plate before they finish cooking.
Add butter and onions to the skillet and cook over medium heat for 12 to 15 minutes until softened and golden, stirring often. Stir in the remaining clean 2 tablespoons flour for 1 minute.
Gradually add broth, Worcestershire, thyme and remaining salt, scraping the skillet. Simmer for 3 minutes, then return chops and their juices and cook gently for 5 to 8 minutes until the thickest pork reaches at least 145°F.
Turn off the heat and rest the chops in the pan for at least 3 minutes. Spoon onion gravy over each serving.