Season and flour the pork: Pat the pork chops dry with paper towels. Season both sides with salt and black pepper. Lightly dredge each pork chop in flour, shaking off any excess.
Sear the pork chops: Heat the olive oil in a large skillet over medium-high heat. Add the pork chops and sear for about 3 to 4 minutes per side, until nicely golden. Transfer to a plate and set aside.
Brown the mushrooms: Add the sliced mushrooms to the same skillet. If the pan looks dry, add 1 tablespoon of the butter. Cook for about 5 to 7 minutes, until the mushrooms release their moisture and develop deep golden edges.
Add the onion and garlic: Add the remaining butter and chopped onion. Cook for about 2 minutes, until the onion begins to soften. Stir in the garlic and cook for about 30 seconds, just until fragrant.
Build the Marsala sauce: Have an adult pour in the Marsala wine. Scrape up the browned bits from the bottom of the skillet and let the wine simmer for about 3 to 5 minutes, until slightly reduced. Pour in the chicken broth and simmer for another 3 to 4 minutes.
Make it creamy: Turn off the heat and let the sauce cool for about 1 minute. Slowly pour in the heavy cream while stirring constantly, then add the thyme. Return the skillet to low heat and let the sauce simmer gently until it starts to thicken. Taste and season with salt as needed.
Finish the pork: Return the pork chops to the skillet along with any juices from the plate. Simmer gently for about 5 to 7 minutes, spooning the mushroom Marsala sauce over the pork as it cooks, until the chops are cooked through and tender.
Finish and serve: Remove the skillet from the heat and let the pork chops rest in the sauce for a few minutes. Spoon plenty of the creamy mushroom Marsala sauce over the top and finish with chopped fresh parsley just before serving.