Whisk together all of the dry ingredients in the large mixing bowl.
Add the eggs and melted butter and mix until a smooth batter forms. Add the buttermilk and stir again until smooth.
Grease the cake pan with butter and then pour the cornbread batter into the pan. Cover well with foil.
Place the Instant Pot® trivet inside the bottom of the Instant Pot® bowl and add 2 cups of water to the bowl as well. Place the wrapped cake pan on top of the trivet.
Cover the Instant Pot® and make sure the steamer valve is set to ‘seal’. Press the ‘manual’ button and set the timer for 50 minutes on high pressure. When the time is complete, let the Instant Pot® naturally release the pressure by just leaving it on the counter to sit! This should take about 10 more minutes before you can easily open the pot! Open the lid and remove the foil from the cake pan. Let cool and then remove the cornbread from the pan. Slice and serve!