Preheat oven to 400 degrees.
In a large oven proof skillet, cook the chopped bacon over medium low heat. Remove from pan, and set aside to drain on a paper towel. Add leeks to the pan and cook in the bacon drippings until soft.
Meanwhile, whip eggs in a large bowl, adding milk, salt and pepper.
Add the bacon back to the pan with the leeks and pour in the eggs. Cook over medium low heat, scraping back the edges occasionally to let uncooked eggs run under.
When eggs are mostly set, place tomato slices on top and bake in oven for 10-12 minutes until completely set.