In a large pot bring about 1 quart salted water to a boil over high heat. Preheat oven to 375 degrees
While the water is boiling, slice the small gold potatoes in half so that they cook quicker.
Once the water comes to a boil, drop your potatoes in the water and cook until fork tender. This will take approximately 20 - 25 minutes. Once the potatoes are fork tender they are ready to be drained.
Prior to draining the water, scoop 2 cups of the starchy water out first and set aside. The starchy water is key in giving the potato mixture a nice and creamy texture. Once you have scooped out the water, drain the remaining liquid out.
Place potatoes in a large bowl and add your milk, greek yogurt, butter (or butter substitute) and 1 cup of the starchy water to start. Season with salt, pepper and garlic powder.
Next take your potato masher and mash potatoes together until they are creamy and all ingredients are incorporated. If you feel the mixture is still tight, slowly add a little of the extra starchy water until you reach your desired consistency.
Next add half of your shredded cheese to the mixture and fold into the mixture.
In a cast iron skillet or casserole dish, spray with Pam. Fold your creamy potatoes into the skillet and spread evenly across the pan.
Next top with the remaining cheese and transfer to the top rack of the oven.
Bake for an additional 10 - 12 minutes or until your cheese is melted and golden brown.