Layer the onions, garlic, salt, pepper, garlic powder, onion powder and and Olive Oil on the bottom of slow cooker.
Next, place the chicken breasts and artichoke hearts in an even layer. Pour chicken stock over the top.
Cover and cook on high for 2½ hours. (add 2-3 hours if cooking on low)
Shred chicken with forks.
Add lemon juice, cream cheese, Greek yogurt and mozzarella.
Remove lid and cook for 30-40 minutes until sauce thickens.
While the sauce is thickening, prepare the garlic buns or pasta.