Slice chicken breasts in half lengthwise. Set aside.
Grease slow cooker and add garlic and oil.
Season chicken with salt and pepper on each side and lay in crock pot.
Pour wine over chicken and cover crock pot.
Cook on high 3 hours or low 7.
Mix water with arrowroot and stir until absorbed, no lumps.
Remove chicken from crock pot and keep warm.
Stir in arrowroot water mixture into the bottom of the crock pot and add mushrooms.
Add back the chicken and stir to coat chicken with sauce and mushrooms,
Cover and cook an additional hour.
Serve with a sprinkle of chopped fresh parsley.