In a large cast iron, heat oil over medium-high heat.
Dredge pork chops in 1/4 cup flour, shaking off any excess. Evenly sprinkle one side of the pork chops with 1/2 teaspoon salt and 1/4 teaspoon pepper. Add the pork chops to skillet, seasoned side down. Cook without moving 6 to 8 minutes. Sprinkle evenly the remaining salt and pepper on the pork chops and turn them over and cook for another 6 to 8 minutes. Remove from the skillet. Cover loosely with aluminum foil and set aside.
Add sage to the skillet and cook until crisp. remove from skillet and set aside. Drain and discard the oil.
Melt butter in skillet. Add garlic and cook stirring frequently, 5 minutes. Add remaining 1/4 of cup of flour to the garlic mixture. Whisk in the milk, whisking frequently until thickened and bubbly. Stir in fresh thyme.
Return the pork chops to pan and garnish with crisp sage leaves.