1Cook pasta al dente, drain well and set aside. While pasta is cooking, combine shredded cheddar, muenster, jack, gruyere in bowl and set aside.
2Pour milk and half and half into a pan (preferably nonstick), over medium heat and bring to a simmer. Add in velveeta cheese and stir constantly until smooth and completely melted. Take about 1/2 cup of the hot milk/cheese mixture and drizzle into the bowl of beaten eggs, whisking with a fork constantly. When you have it all tempered, pour the egg mixture back into the milk mixture, again stirring constantly.
3Butter a 3 qt. baking dish and preheat the oven to 350 degrees. Pour half of the pasta into the dish. Sprinkle with salt and pepper and layer the sliced butter over the top. Sprinkle half of the grated cheese mixture over top of pasta, then pour half of the hot milk/cheese mixture over the top. Repeat this layering one more time.
4Drizzle toasted panko bread crumbs over top and bake at 350 degrees until mac and cheese is bubbly and lightly browned.