Slice the croissants crosswise. Arrange the croissant slices in 3 rows, overlapping the slices, in a generously-buttered 9 x 13-inch deep baking dish.
In a large bowl, combine the eggs, cream, milk, sugar, vanilla, cinnamon, nutmeg, and salt and beat with a rotary beater or whisk until blended but not too bubbly. Pour the mixture over the bread slices, making sure all are covered evenly with the milk-egg mixture. Spoon some of the mixture in between the slices. Cover with foil and refrigerate overnight.
The next day, preheat the oven to 170°C (350°F).
Prepare the Praline Topping. Combine all the ingredients in a medium bowl and blend well. Spread the praline topping evenly over the soaked bread and bake using the bottom heat function for 40 minutes or until puffed and lightly golden. Serve with maple syrup.