Grease your ramekins well with butter or cooking spray (two 6-oz ramekins work best).
Melt chocolate & butter together in a microwave-safe bowl. Heat in 20-second bursts, stirring each time, until smooth and glossy.
Add the egg, egg yolk, and sugar. Stir until smooth.
Mix in vanilla, salt, and flour. Don’t overbeat—just combine until smooth.
Divide batter between ramekins and cover each tightly with foil.
Pour 1 cup of water into the Instant Pot. Place ramekins on a trivet.
Pressure cook on High for 9 minutes. Quick release the pressure when time is up.
Let sit for 2 minutes, then carefully remove and uncover. Serve in ramekins or flip out gently onto plates.
