Pierce the sweet potato with a fork.

Air fry the sweet potato at 375°F for 35–45 minutes, or until fork-tender.

In a bowl, whisk together the egg yolk, sugar, vanilla extract, and cornstarch until smooth.

Slowly add the heavy cream and milk while whisking continuously.

Pour the mixture into a small saucepan.

Cook over low heat, stirring constantly, until it thickens into a smooth custard.

Remove from the heat and let it cool to room temperature.

Slice the cooked sweet potato down the center.

Gently mash the inside with a fork, then push it to the sides to create space for the filling.

Spoon the custard into the center.

Sprinkle a thin layer of sugar over the custard.

Use a kitchen torch to brûlée the sugar until it melts and turns golden brown.