Preheat oven to 350°F. Grease a 9×13 baking dish with 2 tablespoons of butter.
Whisk together eggs, 2 cups of cream, maple syrup, vanilla, cinnamon, nutmeg, and salt.
Dip bread in the custard mixture and Arrange in the prepared baking dish. Pour the remaining custard mixture over the bread. Cover with aluminum foil, and let sit at least 20 minutes for the bread to absorb the mixture. At this point, you can also chill in the refrigerator for 8 hours or overnight.
While bread and custard is resting, combine remaining butter, brown sugar and pecans. Spread the praline mixture over the bread right before putting it in the oven.
Place the baking dish on a large rimmed baking sheet, cover and bake for 30 minutes. After 30 minutes, uncover, return to the oven and bake until golden brown and center is set, about an additional 20-25 minutes.
While the french toast is baking, add remaining cream, maple syrup and vanilla to a medium -sized bowl. Using a handheld mixer, whip the mixture until fluffy.
Serve the french toast warm, topped with whipped cream.