Fill a large pot with water and attach the immersion circulator to the side. Preheat the water to 130°F.
Pat the pork chops dry with a paper towel. Season both sides with salt and pepper. Place the chops into a vacuum-seal bag and use the vacuum sealer to remove all the air and excess moisture.
Place the sealed pork chops into the water bath for 1-6 hours. The pork will become more tender the longer it cooks.
When you're nearly ready to serve the pork, preheat a greased grill skillet on high heat. Place the spinach, butter, mushrooms, and garlic into a vacuum-seal bag. Season with salt and pepper and toss gently to coat the contents with butter. Seal the bag (some butter may be removed in the sealing process).
Place the sealed spinach into the water bath and cook for 10-15 minutes, or until the spinach has halved in size.
Remove the pork from the water bath and take them out of the vacuum bags. Place each chop on the preheated grill for one minute, rotate 90 degrees, grill for another minute, then flip and repeat until the pork has nice grill lines. Do not overcook the pork; if the pan is hot enough, 1-2 minutes per side will achieve nice grill lines.
Remove the spinach from the water bath. Plate the spinach and place the pork chop on top. Season with salt and pepper, serve hot, and enjoy!