Directions Preheat the oven to 350 degrees - Lightly butter a deep 2-1/2 quart casserole.
Bring a large pot of salted water to a boil over high heat. Add the oil, then the elbow macaroni, and cook until the macaroni is just tender, about 7 minutes. Do not overcook. Drain well. Return to the cooking pot.
In a small saucepan, melt 8 tablespoons of the butter. Stir into the macaroni. In a large bowl, mix the Muenster, mild and sharp cheddar and monterey jack cheeses. To the macaroni, add the half and half 1-1/2 cups of the shredded cheese, cubed Velveeta, and the eggs. Season with the sat and pepper. Transfer to the buttered casserole. Sprinkle with the remaining 1/2 cup of shredded cheese and dot with the remaining 1 tablespoon of butter.
Bake until it's bubbling around the edges, about 35 minutes. Serve hot.