ErgoTiger

Depending on your slow cooker, you dont want to cook on warm/low, what every the lowest setting on said slow cooker. Each type is different, and your manual should tell you what the temps are per each setting. For a slow cooker, and just about every raw meat, especially poulty, you want to keep above 170-180F, 200F to be safer while your cooking.

In english:
For less than two pounds, you can usually dry out, over cook or undercook poultry. Keep it simple, and you temperatures right, and get a meat thermometer.

Try this;

1.whole frozen turkey breast "Thawed in the refrigerator 1-3 days"

2.Line the bottom of you slow cooker with raw and cleaned vegetables "like, cut/split taters, onions" with a can of chicken broth or 8oz/one cup water.

3.Wash the thawed turkey breast with cold water, dry with paper towels.

4.Rub turkey breast with real butter or regular olive oil(not Virgin,extra virgin, it will burn".

5.In small bowl mix salt, pepper, garlic powder, or just cheat and using pre-blended Italian or Poulty seasoning, just watch your salt, pre-blends can have salt already in them.

6. Place turkey in slow cooker, ontop of the taters, and then line the slow cooker with carrots or other vegs so that you have something bettween the turkey and slow cooker walls. throw a small piece of aluminum foil ontop of the bird, just big enough to cover the breast.

7.Id say to cook a 2lbs less bird, put on med or low(low is not the same as "warm") cook for 2-3 hours, check after the first two hours, check with meat thermometer, to get you 180F internal temp, pull the breast out of the slow clooker, put in a heavy plate, cover the whole bird, or the top and sides with tin foil and let rest/sit for a good 30mins to and hour before you dig in.