In a small bowl, toss the blueberries with 2 tablespoons of flour. Set aside.
In a large bowl, cream together the butter, cream cheese, sugar, and vanilla until light and fluffy (2–3 minutes).
Add the eggs one at a time, beating well between each addition. Scrape down the bowl as needed.
In a separate bowl, whisk together the remaining 2 cups flour, baking powder, and salt.
With the mixer on low, gradually add the dry ingredients to the wet mixture. Mix just until combined.
Gently fold in the flour-coated blueberries with a rubber spatula.
Lightly grease a 7-inch round push pan (or springform) and pour in the batter. Smooth the top and tent loosely with foil.
Pour 1½ cups of water into the Instant Pot and add the trivet. Lower the pan onto the trivet.
Close the lid, set the valve to "Sealing," and cook on High Pressure for 45 minutes.
Let the pressure release naturally for 15 minutes, then quick-release any remaining pressure.
Carefully remove the pan, uncover, and cool on a wire rack for 15 minutes. Remove from pan and cool completely before slicing.
Slice, serve, and enjoy!