Add all dry ingredients to a large mixing bowl – cornmeal, flour, and salt. Whisk them together.
In a separate mixing bowl – add melted butter and sugar. Whisk together until sugar has melted. Add eggs to butter mixture and whisk until fully combined. Add buttermilk and whisk again.
Pour wet ingredients into bowl with dry ingredients. Stir together until fully combined. A few lumps may remain, and that’s okay.
Spray a 7×3 push pan with nonstick cooking spray. Pour batter into pan and spread out evenly. Cover pan with aluminum foil.
Place 3-inch trivet in cooker, along with 1 ½ cups of water. Place pan on top of trivet. Lock lid and cook for 35 minutes at high pressure.
Once cook time is complete, allow pressure to release naturally for 10 minutes. Then quick-release remaining pressure.
Remove pan from cooker, uncover, and allow to cool for 1 or 2 minutes before slicing.