Heat oven to 400F..Oil a shallow 3 Qt baking dish..Cook the pasta according to directions..when cooked drain and set pasta aside. Chop the bacon and fry until crisp set the bacon aside.
Cut the leeks lengthwise and only cut into the green part for only an inch discard the rest of the green leek..Under running water wash the leeks separating the layers of leek to wash out the dirt..some times there is a lot of soil and sometimes it is quite clean..dry leeks and slice in 1/4 inch pieces saute the leeks until tender about 5 to 8 minutes add the garlic and cook for 2 minutes. Sprinkle the flour over the leeks stirring for 2 minutes.
Whisk in the flour bring to a simmer and add the cream cheese, nutmeg and cayenne ..stir in the cheeses and cook until the cheese has melted.
Combine the cheeses sauce and the pasta and mix until well combined. Sprinkle with the bread crumb mixture and bake in 350F oven until golden about 10 to 15 minutes.