Pat the pork chops dry with paper towels.
Season both sides with the salt, pepper, and garlic powder.
Heat the olive oil in a skillet over medium-high heat.
Sear the pork chops for about 2 minutes per side.
Transfer the pork chops to the slow cooker.
Melt the butter in the same skillet.
Add the minced garlic and stir for 30 seconds.
Stir in the ranch seasoning mix, cream of chicken soup, and chicken broth.
Pour the sauce over the pork chops.
Cover and cook on low for 4 to 5 hours, checking the thickest chop around hour 4.
Stir in the sour cream near the end of cooking.
Mix the cornstarch with the cold water if you want a thicker sauce.
Add the cornstarch slurry to the slow cooker.
Cover and cook for 10 to 15 minutes more, until the sauce thickens.
Sprinkle with chopped parsley before serving, if using.