Make a whole turkey in a slow cooker by cooking it on high for several hours and ensuring that the internal temperature reaches at least 170 degrees Fahrenheit. The turkey must be small enough to cook thoroughly.
To make a whole turkey in a slow cooker, start with a small turkey (it should be less than 9 pounds to be able to fit inside a 6.5-quart cooker) that has been completely thawed. Remove the neck and giblet bag, then pat the turkey with paper towels to dry before rubbing it with olive oil. Season with salt, pepper, dried parsley and garlic powder, then stuff the cavity with sliced apples and onions. Place the bird inside the crock pot, breast side up, and cover.
Cook on high heat, checking the temperature after three hours. It should reach at least 140 degrees Fahrenheit by this point, according to experts at Butterball. Continue to cook on high until the internal temperature reaches a minimum of 170 degrees Fahrenheit. Remove the bird from the slow cooker very carefully and allow to sit for about 20 minutes before carving and serving.
It is important to use a meat thermometer when cooking a whole bird this way to get accurate temperature readings.