Peel and cube potatoes. Add to a large pot of water and bring to a boil. Boil potatoes until just underdone; about 10-15 minutes. While potatoes are cooking, cook bacon; cool, crumble, and set aside. Drain potatoes and set aside.
In the pot you used to cook the potatoes, add butter and melt over medium high heat. Add diced onion, and sauté for 3-4 minutes or until onion has softened and is beginning to turn translucent. Add garlic, salt and pepper, and saute for another minute.
Add flour and whisk until combined with the onion. Slowly whisk in milk and half and half. Whisk until smooth and then slowly whisk in the chicken broth. Bring to a boil and then reduce heat to low and simmer for 5-7 minutes until the mixture has thickened a bit.
Removed from heat and stir in the shredded cheese and Greek yogurt until incorporated. Add the potatoes back into the pot and give it a gentle stir.
Top with bacon crumbles, green onion or chives, and more shredded cheese. Enjoy!