Grease your 9x13 inch baking dish with butter or cooking spray. This prevents the bread from sticking. Make sure you cover the corners well. A well-greased dish makes cleanup much easier later.

Slice your French bread into 1-inch cubes. Do not worry about making them perfect. Place the cubes evenly inside the prepared baking dish. Use a sturdy bread so it holds its shape well.

In a large bowl, whisk the eggs together. Add the milk, heavy cream, sugar, and vanilla. Whisk until the mixture is smooth and combined. This custard is what makes the French toast so creamy.

Slowly pour the egg mixture over the bread cubes. Ensure every piece of bread gets a little bit of liquid. Use a spoon to lightly press the bread down. This helps the bread soak up everything.

Cover the baking dish tightly with plastic wrap. Place it in the refrigerator for at least 8 hours. You can also leave it for up to 24 hours. This step is essential for the best texture.

In a separate small bowl, combine the softened butter and brown sugar. Add the pecans, corn syrup, cinnamon, and nutmeg. Mix until it forms a thick, crumbly paste. This provides that classic Southern praline flavor.

When you are ready to bake, remove the casserole from the fridge. Spread the praline mixture evenly over the top of the soaked bread. It might look thick, but it melts into a beautiful glaze.

Preheat your oven to 350°F. Bake the casserole uncovered for about 40 minutes. The top should be golden brown and bubbly. The center should feel set but still slightly soft to the touch.

Remove the dish from the oven and let it sit. Five to ten minutes of resting helps the flavors settle. It also makes the casserole easier to slice into clean squares. Serve it warm to your guests.