Preheat your oven to high broil.
In a small bowl, whisk together the egg yolk, pumpkin puree, cinnamon, salt, and 1 teaspoon of brown sugar. Set aside.
Spread ½ tablespoon of softened butter on each side of the brioche bread.
Heat a medium-sized cast iron skillet over medium heat. Toast one side of the bread for 1-2 minutes.
Flip the bread and spread the pumpkin mixture over the toasted side. Sprinkle with the remaining brown sugar.
Place the skillet in the oven (middle shelf) and broil for 2-3 minutes until the brown sugar melts.
Remove the toast from the oven and let it rest for 5 minutes to allow the melted brown sugar to harden.
Crack the hardened brown sugar with a spoon or knife for that classic crème brûlée crack, then enjoy!