Fry bacon until crisp; drain and crumble. Set aside. Preheat oven to 350°F. Cook pasta according to al dente package directions. Drain well; set aside
In large bowl, combine milk, eggs, sour cream, garlic salt, white pepper, onion powder and paprika. Whisk together until mixed well. Stir in cooked pasta and cheeses, reserving 1 cup cheddar. Pour into deep baking dish. Sprinkle remaining cheddar evenly over top.
Bake 20-25 minutes. Remove when edges are golden brown. Let macaroni and cheese set 10 minutes; then garnish with crumbled bacon and chopped chives or green onion.