Preheat oven to 350 degrees F. Butter or spray a 9x13 inch glass dish. Cut French bread into 1 inch cubes and spread evenly into the bakeware. Set aside while you prep other ingredients.
Over medium heat, cook the sausage in a large skillet until it's no longer pink. Drain and set aside to cool.
In the same skillet, add 1 or 2 tablespoons of olive oil, mushrooms, garlic and onion. Stirring often, cook for 3-4 minutes until the mushrooms have softened and onions are translucent. Add chopped kale and cook an additional 2 minutes until slightly wilted. Turn off heat and set aside while you prep your egg mixture.
In a large bowl, whisk together eggs, milk cream, mustard, salt and pepper.
To the egg mixture, stir in the cooled sausage, and vegetable mixture. Pour entire mixture over the bread that is in your baking dish. Sprinkle the top with the Asiago cheese and additional black pepper, if desired. Bake in the oven for 30-35 minutes or until a knife inserted in center comes out clean.