Preheat your oven to 350°F and lightly butter a 9x13 inch baking dish (or similar size). While the oven heats, peel and slice the potatoes into 1/8-inch rounds—I like to use a mandoline for this to keep the slices consistent, which helps them cook evenly. Slice the onion into thin rounds as well. Shred the cheddar cheese fresh if you haven't already, as freshly shredded cheese melts much more smoothly than pre-shredded varieties.

In a large bowl, combine the sliced potatoes and onions with the milk, shredded cheese, salt, black pepper, and garlic powder. Toss everything together gently until the potatoes and onions are evenly coated and the cheese is distributed throughout. Pour this mixture into your prepared baking dish, spreading it in an even layer. Dot the top with 4 tablespoons of butter cut into small pieces, distributing them across the surface so the butter melts throughout as it bakes.

Pat the pork chops dry with paper towels and season both sides evenly with salt and black pepper. Arrange the seasoned pork chops directly on top of the scalloped potato mixture, spacing them out so heat can circulate around each chop. I prefer bone-in, 1-inch thick chops because they stay juicier during the longer bake time and look more impressive at the table.

Place the baking dish in the preheated 350°F oven and bake for 25 minutes. Then carefully flip each pork chop to the other side and return to the oven. Continue baking for another 25-30 minutes, until the pork chops are cooked through (internal temperature of 145°F) and the potatoes are tender when pierced with a fork.

Remove the baking dish from the oven and let it rest for 5 minutes. Check that the potatoes are fully soft and creamy—if they're still firm in the center, return the dish to the oven for another 10-15 minutes. The pork chops should be golden and cooked through with an internal temperature of 145°F at the thickest point. Let the pork rest in the dish for a few minutes before serving; this keeps the meat juicy and allows the residual heat to finish cooking the potatoes evenly.