Put the potatoes and garlic in a large pot with salt and enough water to cover; bring to a boil. Cover and reduce heat; simmer for 20 minutes or until potatoes are tender. Drain and return potatoes and garlic to pan. Add sour cream and remaining ingredients. Using a masher or blender, mash until smooth. Season with salt and pepper to taste.
Meanwhile, preheat the oven to 350°. Line a muffin tin with foil liners.
In a large bowl, mix the turkey, zucchini, onion, breadcrumbs, ketchup, egg, and salt. Place meatloaf mixture into muffin tins filling them to the top, making sure they are flat at the top.
Bake uncovered for 18-20 minutes or until cooked through. Remove from tins and place onto a baking dish.
Pipe the “frosting” onto the meatloaf cupcakes and serve.