SLOWLY whisk the brown sugar, melted butter, vanilla, and milk together for about 1 minute.
Then, SLOWLY stir in the baking powder, flour, and salt until no white streaks remain.
Fold in the chocolate chips.
Spray your silicone egg bites mold with non stick cooking spray. (Use your finger inside each cup to make sure there's good coverage.)
Spoon the batter into each mold. Each cup should be about 3/4 full.
Cover the mold with the pressure cooker safe lid (or with foil, if you don't have a mold cover.)
Pour 1 cup of water into the bottom of the Instant Pot, and place the mold on top of a trivet.
Set the lid valve to SEALING, and set pressure cook for 12 minutes on high pressure.
When the time is up, do a natural release for 10-15 minutes before venting.
Put a plate on top of the mold and flip it over to release the mini muffins.