Start by cutting the loaf of bread into 1-inch cubes. If the bread is fresh, it’s best to leave it out for a few hours or overnight to dry out a little—stale bread works best for this recipe as it absorbs the custard mixture better. Brioche, challah, or French bread are excellent choices for a rich and soft texture. If you don't have stale bread, lightly toast the cubes in the oven for about 5-7 minutes until they’re just a little crisp.

In a large mixing bowl, whisk together the eggs, whole milk, heavy cream, granulated sugar, vanilla extract, ground cinnamon, and salt. Make sure the mixture is smooth and fully combined. The eggs provide the custardy texture, while the vanilla and cinnamon bring out the flavor, making this the perfect base for your casserole.

Add the prepared bread cubes to the egg mixture and gently stir to coat them evenly. Be sure the bread soaks up the custard mixture, but don’t over-stir to avoid breaking the bread into mush. Let the bread sit in the mixture for about 5 minutes to absorb the custard, which will help create that delicious, custardy texture when baked.

Once the bread cubes are soaked with the custard, transfer them into a greased 9x13-inch baking dish. Spread them out evenly to ensure that every piece of bread is submerged in the egg mixture. If you prefer a more rustic look, you can gently press the bread into the dish so it fits snugly.

If you have time, cover the baking dish with plastic wrap and refrigerate it overnight. This step is optional but highly recommended. Allowing the casserole to chill gives the bread even more time to soak up the custard, resulting in a richer texture. If you're short on time, you can skip this step and bake the casserole right away.

Preheat your oven to 350°F (175°C). Bake the casserole uncovered for 45 minutes, or until the top is golden brown and the edges are slightly crispy. The center should be set, and a toothpick inserted should come out clean. Keep an eye on it while baking to avoid over-baking.

Once the casserole is baked, remove it from the oven. You can add a sprinkle of powdered sugar for a little sweetness and presentation. If desired, top with fresh berries, whipped cream, or your favorite syrup. The added toppings not only enhance the flavor but also give it a delightful visual appeal.

Cut the casserole into squares and serve warm. This dish is perfect on its own or paired with maple syrup or a dollop of whipped cream for extra indulgence. It’s ideal for a brunch gathering or a comforting breakfast to start your day.