Directions
1.    Preheat oven to 400 degrees. Spray a 9 x 13 glass baking dish with nonstick spray. Slice meatballs in half and place, cut side down, evenly in the bottom of the prepared pan. Set aside.
2.    Heat milk in a microwave safe dish or cup 1-2 minutes or until it becomes hot, but not boiling. Set aside.
3.    Melt butter in a large skillet over medium heat. Add onion and cook 3-5 minutes until softened. Add 2 Tbsp. of the white wine and continue stirring and cooking until onion becomes golden brown. Sprinkle flour over onion mixture and cook, stirring constantly, another 3-4 minutes. Remove pan from heat. Whisk in milk all at once. Return pan to stove and continue cooking another 4-5 minutes until sauce thickens. Season with salt and pepper. Stir in remaining tablespoon of wine. Remove from heat and add the sour cream and 1-3/4 cups of cheese. Set aside.