In a 5 qt. saucepan, add enough water to reach 2/3 full. Place on the stove and put on medium-high heat. Cover and bring to a boil. Prepare the pasta as directed on the box. Drain well when done. Meanwhile, in a 3 qt. saucepan over medium-low heat, melt the butter. Add the garlic powder and cream cheese; whisk together until creamy and smooth. Pour in a little bit of milk at a time, continuing to whisk, until all incorporated. Add the shredded cheese and salt & pepper to taste. Continue to stir/whisk until you get your desired thickness. If the consistency is too thick, just add more milk.