Lightly grease a 9x13 inch (23 x 33 cm) glass baking pan.
Cut the loaf of bread into small cubes or rip into pieces with your hands. Place the bread in the prepared pan.
In a large bowl, whisk together the milk, pumpkin puree, eggs, sugar, pumpkin spice and vanilla extract.
Pour the pumpkin mixture over the bread and gently stir (if needed) to ensure that the bread is evenly coated.
In a medium bowl stir together the flour, brown sugar, white sugar, pumpkin pie spice and chopped pecans.
Stir in the melted butter.
If Baking Immediately
Preheat the oven to 350F (180C) degrees.
Sprinkle/crumble the streusel over the French toast casserole.
Cover the pan with aluminum foil and bake for 40 minutes covered. Then remove the foil and continue baking for 15-20 minutes, or until an inserted toothpick comes out clean.
If Baking the Next Morning
Cover the pan with aluminum foil and place in the fridge overnight.
Cover the bowl of streusel with plastic wrap and place in the fridge.
When ready to bake, remove from the fridge and preheat the oven to 350F (180C) degrees.
Sprinkle the streusel over the French toast casserole.
Bake covered with aluminum foil for 40 minutes, then remove the foil and continue baking for 15-20 minutes.
*To make your own pumpkin pie spice, use 2 teaspoons cinnamon, 1/2 teaspoon nutemg, 1/2 teaspoon ginger powder, and 1/4 teaspoon ground cloves. Store leftovers covered in the fridge. Then warm up in the microwave before enjoying. Leftovers can also be frozen. Cut into pieces, place in a freezer safe container and freeze for up to 2 months. Thaw in the fridge overnight, then warm up in the microwave to enjoy.Recipe can also be halved and prepared in an 8x8 or 9x9 inch pan (just ensure the sides are high).