Prep work: Preheat your oven to 350°F Grease a 2 quart baking dish. Toss together the colby and mozzarella. Reserve 1/2 cup of the cheese mixture for the topping.
Bring a large pot of water to boil. Boil the macaroni until al dente, according to package directions (usually 8-10 minutes). Drain and set aside.
In a small saucepan, heat up the milk - do not let it boil. Whisk in the dry mustard, Worcestershire, salt, and hot sauce. Remove from the heat.
Stir in the butter and cheeses (except for the reserved) to the drained macaroni. Put the macaroni into the greased baking dish. Pour the hot milk mixture over the macaroni. Top with the reserved 1/2 cup of cheese. Sprinkle with paprika if desired.
Bake for 30 minutes, and then place under the broiler 1-2 minutes to lightly brown the top.