1-Add the milk, pumpkin puree, granulated sugar,: Add the milk, pumpkin puree, granulated sugar, brown sugar, vanilla, pumpkin pie spice, and eggs to a large mixing bowl. Whisk until combined and no streaks of egg are visible.
2-Generously spray a 9×13-inch baking dish with: Generously spray a 9×13-inch baking dish with nonstick cooking spray. Spread the cubed French bread evenly in the prepared baking dish.
3-Pour the pumpkin mixture over the cubed: Pour the pumpkin mixture over the cubed bread. Use a fork or spoon to gently press the bread cubes into the pumpkin mixture so they can absorb the custard. Cover the baking dish and refrigerate for at least 3 hours or overnight.
4-When you are ready to bake the: When you are ready to bake the casserole, preheat the oven to 350°F.
5-To make the streusel topping, add the: To make the streusel topping, add the cold cubed butter, brown sugar, flour, and pumpkin pie spice to a food processor. Pulse until the mixture resembles coarse sand. If you don’t have a food processor, use a pastry blender. Transfer the streusel mixture to a medium bowl and stir in the chopped pecans.
6-Remove the casserole from the refrigerator and: Remove the casserole from the refrigerator and evenly sprinkle the streusel topping over the top.
7-Bake for 55-60 minutes, checking the casserole: Bake for 55-60 minutes, checking the casserole at 55 minutes. The center should be set and should no longer look loose or wet when gently checked with a knife. Do not rely on a clean toothpick alone for doneness, as our testing found that a toothpick could come out clean while the center was still wet. If the streusel begins to brown too much before the center is set, loosely cover the top with aluminum foil.
8-Remove the casserole from the oven and: Remove the casserole from the oven and allow it to cool for 30 minutes before slicing. Drizzle with maple syrup, if desired, and serve with vanilla ice cream or thawed whipped topping.