Clean and cut chicken breasts into small chunks. Place chicken and next 8 ingredients (through garlic) in a crockpot, stirring well.
Lightly spoon flour into measuring cup, level. Place flour in small bowl, gradually add chicken broth, stir with a whisk until blended. Add broth mixture to crockpot slowly, stir well. Cover with lid, cook on high setting for 1 hour. Reduce to low setting and cook 5 hours. Add whole wheat noodles and cook for 1 more hour on low. Let stroganoff stand 10 minutes and then stir in Greek yogurt.
Another option is to boil the noodles separately and add with the Greek yogurt just before serving.