Preheat oven to 350°F (177°C).
Grease an 8×8 inch or any 3-4 quart oven-safe dish with nonstick spray.
Cut the entire challah loaf into 1″ cubes. Spread half of the cubes into the baking pan.
Using a handheld or stand mixer fitted with a whisk attachment, beat the room-temperature cream cheese on medium-high speed until completely smooth and a bit fluffly.
Then, beat in the confectioners’ sugar and 1/4 teaspoon vanilla extract until combined into the cream cheese mixture.
Drop spoonfuls of cream cheese mixture on top of the first layer of bread. Make sure the cream cheese mixture is spread out throughout the pan.
Add the remaining bread cubes on top.
Whisk the eggs, plant-based milk, pumpkin spice, brown sugar, pumpkin and remaining vanilla together until smooth.
Pour the mixture over the bread, and turn the mixture with a spoon, being careful not to squish the bread too much.
Prepare the crumb topping: Whisk the brown sugar, nuts, and pumpkin spice together in a medium bowl. Cut in the cold cubed butter with two forks. Sprinkle the topping evenly over the soaked bread.
Bake uncovered for 50-55 minutes or until golden brown on top, or a knife scraped over the top makes that super satisfying crunch. Drizzle with optional maple syrup or dust with confectioners’ sugar. Serve warm.
Cover leftovers tightly and store in the refrigerator for 2-3 days, or freeze and re-heat for up to two weeks.