Place the leeks and bacon into a medium-sized saute pan and cook over medium heat for about 10 minutes.
Meanwhile, preheat the oven to 350 degrees.
Place the cornbread into a greased 9×12 baking dish and set aside.
Crack the eggs into a medium-sized bowl. Lightly beat the eggs and then add the milk, cream, lemon zest, mustard, salt, herbs and cheese into the bowl.
Add the bacon and leeks to the bread mixture and stir well to combine.
Pour the custard over the bread mixture and mix well.
Bake for 1 hour or until the eggs are cooked through. Serve warm with a summer fresh tomato salad.