Cook spaghetti with salt; drain. Add melted butter and evaporated milk or heavy cream mixed with garlic. Fold in warm red enchilada sauce. Add salt and pepper to taste. Spoon into a long baking dish. Sprinkle with mixed cheeses and oregano. Bake, covered, at 325 degrees F, until bubbling, about 15 minutes. Check often as red sauce tends to scorch easily.