Layer whole pepperoncini on the bottom of a slow cooker. Sprinkle the olive slices and garlic on top of the peppers.
Rinse chicken and pat dry. Place on top of pepperoncini mixture. Sprinkle chicken with 1 1/2 teaspoons paprika, the salt, pepper and lemon zest. Slowly pour in lemon juice.
Cover and cook on low 6 to 6 1/2 hours or until meat easily pulls away from bone. Remove chicken to a warm plate and cover to keep warm.
Turn slow cooker on high. Skim fat from cooking liquid. Whisk in sour cream until blended. Cover and simmer on high until heated through 8 to 10 minutes depending on your cooker. Stir in pepper and paprika.