Place a large skillet over medium heat and add 2 tablespoons of butter
Add a medium diced yellow onion, 2 large finely minced cloves of garlic and 8 ounces of sliced mushrooms and sauté until tender (5-6 minutes)
Add 2 cups of thinly sliced kale, cover the skillet and cook until the kale has wilted down a bit (another 2-3 minutes)
Transfer the skillet off of the heat
In a large bowl, toss the torn bread, sautéed vegetables, herbs, 1 cup of shredded fontina and 1 cup of shredded parmesan until evenly distributed and spread the mixture into a buttered 2 quart baking dish (an 8”x8” or similar)
In the same bowl, whisk 8 large eggs with 1 cup of whole milk, 1 cup of heavy cream, 2 teaspoons of dijon mustard, 1 teaspoon of salt, 1/4 teaspoon of black pepper and 1/4 teaspoon of nutmeg
Pour the cream mixture over and press down a bit on the bread until it has all soaked up some of the mixture
Set the baking dish aside for about 30 minutes and preheat your oven to 350°
Tightly cover the strata with foil
Bake covered in a 350° for 20 minutes
Uncover the dish and bake for an additional 20 minutes or until the custard is set