In a large bowl, whisk together milk, brown sugar, maple syrup, eggs, pumpkin, cinnamon, ginger, cardamom, nutmeg, and salt until well blended.
Add bread and stir carefully to combine, making sure there are no dry pieces remaining.
Lightly coat an 8x8 square baking dish with nonstick spray. Pour the bread into the dish, arranging evenly in the pan. Pour any leftover custard over the top.
Cover with plastic wrap and let sit at room temperature for 30 minutes, or in the refrigerator overnight.
When ready to bake, preheat oven to 350°F. Remove plastic wrap and bake for 35-40 minutes.
Let cool slightly and serve with your favorite topping.