1: Prepare the Brioche Bread

1. Slice your brioche bread into 1-inch cubes. If the bread is fresh, lightly toast the cubes in the oven at 300°F for 5–7 minutes to dry them out. This step helps prevent the casserole from becoming soggy.
2. Grease a 9×13-inch baking dish with butter or non-stick spray. Spread the cubed brioche evenly across the dish.

 2: Make the Custard Mixture

1. In a large mixing bowl, whisk together the 6 eggs, 2 cups whole milk, and ½ cup heavy cream.
2. Add the sugar, vanilla extract, cinnamon, nutmeg, and a pinch of salt. Whisk until the mixture is smooth and fully combined.
3. For a lump-free custard, you can strain the mixture through a fine-mesh sieve.

 3: Assemble the Casserole

1. Pour the custard mixture evenly over the cubed brioche, making sure every piece is coated.
2. Use a spatula or your hands to gently press the bread into the custard, ensuring it absorbs the liquid.
3. Cover the dish with aluminum foil and let it sit for at least 30 minutes. For best results, refrigerate the assembled casserole overnight to allow the flavors to meld.

 4: Bake the Casserole

1. Preheat your oven to 350°F (175°C). Remove the casserole from the fridge (if refrigerated) and let it sit at room temperature while the oven preheats.
2. Bake the casserole covered with foil for 25–30 minutes. Then, remove the foil and bake for an additional 15–20 minutes, or until the top is golden brown and crispy. A knife inserted into the center should come out clean.

 5: Add Toppings and Serve

1. Let the casserole cool for about 5–10 minutes before serving.
2. Top with fresh strawberries, blueberries, and a dollop of whipped cream. Dust with powdered sugar if desired, and drizzle with warm maple syrup for the finishing touch.