Smear the inside of each ramekin with a little soft butter. Sprinkle 1 teaspoon sugar into each ramekin. Rotate ramekin around to ensure entire ramekin is coated with sugar. Set aside.
Melt butter and chocolate chips in microwave safe dish - 50% power for 1-2 minutes for most microwaves. Set aside.
Blend eggs and egg yolk in medium bowl. Add vanilla and melted butter and chocolate. Mix well.
Add powdered sugar, flour, salt and cayenne pepper. Mix well until a thick batter forms.
Set trivet into inner pot of the Instant Pot. Add ¾ cup water. Pour batter evenly into prepared ramekins and set ramekins side by side on trivet.
Secure lid, ensuring the valve is pointed to sealing. Press pressure cook and set timer to 9 minutes.
When timer goes off, turn valve to venting to release the pressure. When all pressure is released, carefully remove lid and take out ramekins using oven mitts.
Let ramekins sit for 5 minutes. Run a small knife along the inside of the ramekins to loosen lava cake. Carefully place a small plate over one of the ramekins and invert so the lava cake comes out of the ramekin and sits upside down on the plate. Repeat for other ramekin. Top with sifted powdered sugar, a raspberry, a sprig of mint, and serve warm.