Preheat your oven to 375°F (190°C). Lightly grease a 9x13 baking dish.

Pat the pork chops dry with paper towels. Season both sides with salt, pepper, and garlic powder. Sprinkle thyme over each chop.

Heat 2 tablespoons olive oil in a large skillet over medium-high heat. When hot, add pork chops and sear for 4–5 minutes per side until golden brown. They don’t need to be fully cooked through — we'll finish them in the oven. Transfer chops to a plate and tent with foil.

In the same skillet, reduce heat to medium and add 3 tablespoons butter. Once melted, add the minced garlic and chopped onion (if using). Sauté for 1–2 minutes until fragrant — don’t let the garlic burn.

Sprinkle 1 tablespoon flour over the butter-garlic mixture and stir for 30 seconds to make a light roux. Slowly whisk in the heavy cream and milk. Simmer for 2–3 minutes until the sauce begins to thicken. Taste and season with a pinch of salt and pepper.

Layer half of the sliced potatoes in the prepared baking dish. Pour half of the cream-garlic sauce over that layer. Add the remaining potatoes and pour the rest of the sauce on top. Sprinkle cheddar and Parmesan evenly across the casserole.

Cover the baking dish tightly with foil and bake for 30 minutes.

Meanwhile, return the skillet to medium heat just to rewarm the pork chops briefly (optional).

After 30 minutes, remove foil and nestle the seared pork chops on top of the potato casserole. Return the dish to the oven, uncovered, and bake for another 15–20 minutes, or until potatoes are tender (test with a fork) and the top is golden and bubbly. Pork chops should reach an internal temperature of 145°F (63°C).

Remove from oven and let rest 5 minutes. Garnish with chopped parsley or chives and serve hot with steamed greens or a crisp salad.