Preheat oven to 375°F. Grease a 9 x 13″ baking dish. Add the torn bread to the dish. In a large bowl, whisk the eggs until fully incorporated and frothy. Whisk in the milk, cream, sugar, vanilla extract, 1/2 tablespoon cinnamon, nutmeg and kosher salt. Pour the custard over the bread pieces and use your fingers to submerge the tops of the bread to ensure it is all coated. Rest 20 minutes at room temperature (or refrigerate overnight and bring to room temperature for 20 minutes before baking). Meanwhile, in a medium bowl, add the rolled oats, pecans, turbinado sugar, flour, and 1 teaspoon cinnamon. Cut the butter into the other ingredients using a pastry cutter or fork until evenly combined and a crumbly streusel topping forms. Refrigerate until baking. Just before baking, sprinkle the streusel topping over the French toast. Bake 40 to 45 minutes until browned and set. Rest 10 minutes before serving. Scoop out pieces and top with a drizzle of maple syrup.