To make the caramel, heat the ⅓ cup of sugar over low heat, stirring regularly until it starts to melt.
Cook until it thins and becomes a very light brown color, then pour in the bottom of a 6" non-stick cake pan. Set aside.
Whisk the eggs and egg yolks in a bowl. Set aside.
Heat the milk, cream, vanilla, salt and sugar in a saucepan over medium-low heat for 3-5 minutes, whisking constantly to ensure the milk doesn't scald. Remove from heat.
Temper the eggs by pouring a couple of tablespoons into the egg mixture while whisking constantly.
Continue to add more of the hot liquid to the egg mixture while whisking constantly until it has been fulling combined.
Pour the custard mixture over the caramel in the cake pan and cover with aluminum foil.
Place 1 cup of water in the bottom of the Instant Pot.
Place the cake pan on the trivet and slowly lower into the Instant Pot.
Cook at high pressure for 12 minutes, then let the pressure release naturally for 10 minutes. Release any remaining pressure.
Remove the foil and cool for 1 hour at room temperature. Place in the fridge and chill at least 6 hours before serving.
Notes
When melting the sugar to make the caramel, stir it frequently so it doesn’t burn.
Make sure you temper the eggs! This will ensure the eggs don’t cook or curdle as they’re combined with the hot milk mixture to make the custard.
Be sure to let the pressure naturally release for 10 minutes. The flan will continue cooking during this time.
Don’t leave the flan in the Instant Pot after the pressure has been released. It will overcook.
While the cooking time is just 12 minutes on high in the Instant Pot, you’ll also need to factor in time for pressure to build and release.
Chilling is key to ensuring the flan sets up and releases from the pan without breaking apart.
To help the flan release from the pan, run a knife around the edges to loosen the sides.
When removing the flan from the pan, be sure to invert it on a serving plate so the soft caramel is on top.