Place pork loin in a bowl or large container and season with 2 tsp salt, 2 tsp pepper, and garlic powder. Rub into all sides.
Cover and place in refrigerator for 20-40 minutes (or longer if you wish). Preheat oven to 425℉.
Slice apples and onions and chop garlic. Take pork loin out of the refrigerator and add onions, apples and garlic.
To that, add honey, oil, the remaining 1 tsp salt and 1 tsp pepper and cinnamon
Place a layer of apples and onions at the bottom of a 9x13 baking dish. Put pork loin on top.
Add the remaining apples and onions around it. Add about 1 tbsp soften butter to top of pork loin and break up remaining butter into pieces and put on top of apples.
Bake for 30 minutes. Reduce heat to 350℉ and continue to bake for 30 minutes.
Take out of oven and stir/toss apple and onion. Turn heat up to 450℉ and bake for 10 more minutes.
Enjoy!