Whisk cream, half-and-half, scraped vanilla seeds, and vanilla pod in a saucepan. Place over medium heat and bring just to a boil. Remove from heat and add chai tea bags to the cream mixture; cover and let steep for 15 minutes. Squeeze tea bags and discard; discard spent vanilla bean pod.
Preheat oven to 300 degrees F (150 degrees C).
Whisk egg, egg yolks, and 1/2 cup sugar in a bowl until smooth. Slowly whisk in cream mixture, followed by cinnamon, cardamom, cloves, nutmeg, and allspice.
Spoon cream mixture into 6 6-ounce ramekins. Bring a pot of water to a boil. Place ramekins in a baking pan and carefully pour enough boiling water into the pan to reach halfway up the sides of the ramekins.
Bake in the preheated oven until the desserts are softly set, 35 to 40 minutes. Remove ramekins from the water bath and refrigerate for 4 hours to overnight.
Sprinkle each dessert with about 1 1/2 teaspoon sugar in an even layer. Use a kitchen torch to lightly brown and caramelize the sugar, about 1 minute; let the hot topping cool and harden before serving.