1 cup mayonnaise
1/4 cup shredded Parmesan cheese
3 cloves garlic, minced
1/4 teaspoon red pepper flakes
1/2 teaspoon paprika
1/4 teaspoon salt
1/4 teaspoon ground black pepper
3 large baking potatoes, cut into 1/4-inch slices
1 large sweet onion, sliced
4 12×12-inch squares aluminum foil
Preheat grill for medium heat and lightly oil the grate.
Stir mayonnaise, Parmesan cheese, garlic, red pepper flakes, paprika, salt, and pepper together in a large bowl. Add potatoes and onion; stir to coat completely.
Arrange aluminum foil squares on a work surface and spray each with cooking spray. Divide potato mixture between the four squares. Fold aluminum foil over potato mixture and crimp edges together to form a secure pouch.
Cook on the preheated grill until potatoes are tender, about 30 minutes.