Spray a 9x13 pan with cooking spray and preheat your oven to 350 degrees. In a large bowl, add the eggs, milk, heavy cream, sugar, 1/2 cup brown sugar, vanilla, cinnamon and nutmeg. Chop the bread into 3/4 - 1 inch cubes and put it in the bowl with the egg mixture and toss well until all the liquid is absorbed. In a small bowl or a food processor add the flour, brown sugar, cinnamon, and salt and mix. Cut in the butter with a fork or pulse in the food processor for 5-10 seconds or until the butter and brown sugar mixture is crumbly. Pour the bread and egg mixture into the pan, cover evenly with the brown sugar-butter topping and bake for 45-50 minutes or until the top is crispy and the center is no longer wet.