Prep: Preheat the oven to 325°F. Place 4 ramekins on a baking tray and set aside. Boil a kettle or pot of water while you prepare the recipe.
Heat cream: In a small pot on the stovetop, heat the whipping cream on low-medium heat until small bubbles start coming to the surface and it just begins to simmer.
Mix egg yolk mixture: Meanwhile, in a large mixing bowl, whisk together egg yolks, sugar, pumpkin purée, vanilla extract, pumpkin pie spice, and salt.
Whisk hot cream into egg mixture: Slowly stream the hot cream into the egg mixture while whisking constantly and vigorously with your other hand until all the cream has been added.
Fill ramekins: Use a ladle to spoon this mixture into your ramekins until they're almost full. Dab a paper towel on any air bubbles to get rid of them. Very carefully transfer the entire tray of ramekins into the oven.
Make water bath: Before pushing the tray all the way into the oven, fill the baking tray with hot water from a kettle until the ramekins are submerged about halfway (about ½" of water).
Bake: Bake for about 28-30 mins or until the edges are set but the custard is still very jiggly.
Chill: Carefully remove the tray from the oven and pour off most of the water in the pan. Let the custards cool completely at room temperature. Cover and chill them in the fridge for at least 2 hours or overnight.
Add sugar topping: Let the custards sit at room temperature for about 30 minutes before adding the sugar topping. Right before serving, sprinkle the surface of each custard with an even layer of 2 teaspoons of sugar.
Caramelize sugar: Use a kitchen torch to caramelize the sugar topping until golden brown and bubbling. Let them cool down and harden before cracking into them with a spoon.