Preheat oven to 350 degrees F. Grease a 9x13" baking dish with cooking spray and set aside.
In a large skillet melt butter.
Add leeks and cook over medium heat until very soft, about 15 minutes.
Meanwhile, in a large bowl, combine 2 cups of the milk with the cubed bread. Set aside and let stand until the liquid has absorbed, about 10 minutes.
In a separate bowl, whisk together remaining 1 1/2 cups of milk, eggs, garlic, salt, pepper, nutmeg, sage, and herbs de Provence until well blended.
You can assemble the strata once the leeks have cooked and the bread has soaked.
Place half of the bread mixture into the prepared dish.
Top with half of the leeks, half of the goat cheese, half of the ham, half of the artichoke hearts, and half of the cheese.
Pour half of the milk/egg/herb mixture over.
Repeat with remaining layers of bread, leeks, goat cheese, ham artichoke hearts, cheese, and milk/egg mixture.
If you are going to bake this in the morning, cover and refrigerate.
If you are baking immediately, place in preheated oven, uncovered, for about 1 hour until the center is firm and the edges are brown.
If you are going to bake in the morning, I recommend removing it from the refrigerator an hour prior to baking, or just add 10-15 minutes to the baking time.
Serve and enjoy!