NOTE: on the shredded cheeses - each 8 ounces of shredded cheese is equal to 2 cups. So you will have 2 cups EACH of sharp cheddar, monterey jack, and colby - 6 cups total.
Set aside 1/2 to 1 cup of the sharp cheddar cheese - you will use this to top the macaroni and cheese. If you like a lot of cheese on top, set aside a cup. If you just want a sprinkle of cheese on top, set aside half a cup.
Preheat the oven to 350º F.
Cook the macaroni to the "al dente" stage, according to the package directions. Drain well and set aside.
In a large mixing bowl, beat the eggs together with the milk and the evaporated milk. Add the dried mustard, hot sauce, and salt and mix well.
Add the cooked, drained macaroni to the milk mixture. Add the melted butter and the sour cream and mix well.
Add the shredded sharp cheddar, monterey jack, colby, and the velveeta to the macaroni and mix well, stirring for a minute or two to make sure all the ingredients are well combined.
Pour the macaroni mixture into a greased 9 inch by 13 inch casserole dish, and top with the reserved shredded sharp cheddar.
Bake at 350º for 45 minutes or until the top is lightly browned.