Preheat the air fryer to 350F (175C). Then, place a saucepan over medium heat.Add the heavy cream, vanilla extract, and salt. Mix and cook until the heavy cream simmers. Remove from the heat.
Place the eggs in a mixing bowl and mix them with the sugar until well combined.Then, temper the eggs- slowly pour about 1/2 of the warmed heavy cream mixture into them while whisking.
Pour this mixture into the remaining heavy cream mixture and keep whisking. Then, divide between all the ramekins.
Bake in the air fryer for about 20-25 minutes (don’t overcrowd the air fryer, cook in batches if needed). Check the center of the filling to make sure they are cooked through.
If you want to crust the top of the creme brulees, spread out granulated sugar evenly over them. Then, using a kitchen blow torch, caramelize the sugar.