Line your slow cooker with a large sheet of aluminum foil.
In a large bowl, toss red potatoes with olive oil, 1/2 Parmesan cheese, lemon zest, lemon juice, and parsley.
Add potatoes to slow cooker and seal aluminum foil around them.
Cook on high 3-4 hours or until fork tender.
Toss with remaining Parmesan and season with salt and pepper before serving.