Preheat oven to 350 degrees. Spray a 13" x 9" pan with cooking spray.
Cut bread into 1 inch cubes and set aside.
In a large bowl, whisk together canned pumpkin, milk, eggs, vanilla and pumpkin pie spice.
Gently stir bread cubes into the pumpkin mixture, just until all of the cubes are coated.
Pour bread and pumpkin mixture into a 13" x 9" pan and spread evenly.
In a small bowl, mix cold butter, sugars, flour and cinnamon using a fork or even your fingers until it resembles coarse crumbles. Stir in chopped pecans if using. Sprinkle over bread mixture.
Bake uncovered for 40-50 minutes or until top is nicely browned and french toast is set.
Notes
Use day-old bread for best texture.
Soak briefly before baking for custardy centers.
Bake uncovered for golden, crisp edges.
Optional: Add chopped pecans for crunch.
Storage: Store leftovers in an airtight container for up to 3 days.
Freeze: Store individual portions, tightly wrapped in containers, for up to 2 months.
Reheat: Warm in the microwave or oven until heated through.
Make-Ahead: Assemble the night before (without streusel), refrigerate, then top and bake in the morning.