Preheat your oven to 350°F (175°C) and lightly grease a 13x9 inch baking pan with non-stick spray.

Cut your French bread into 1-inch cubes and spread them in a single layer on a baking sheet.

In a large skillet, heat over medium-high heat and add the crumbled mild Italian sausage. Sauté for about 5-7 minutes until fully cooked and browned.

Using the same skillet, add a splash of olive oil and sauté diced onions for 2-3 minutes, then stir in the diced apples and cook for an additional 3-4 minutes.

In a large mixing bowl, whisk together the large eggs, milk, heavy cream, kosher salt, ground nutmeg, ground sage, and freshly cracked pepper.

Begin layering by placing half of the dried bread cubes in your greased baking dish, followed by half of the cooked sausage and the apple-onion mixture.

Pour the egg and milk custard mixture evenly over the layered ingredients in the baking dish.

Sprinkle half of the shredded Gruyère cheese over the top of the pudding mixture.

Place the baking dish in your preheated oven and bake for 50-60 minutes, or until the top is golden brown.