With your Instant Pot on Sauté function, add the butter and when it is just melted, then sauté the chicken and garlic in the pot for 2-3 minutes, stirring regularly to lightly cook the sides of the chicken.
Add pasta and chicken broth, stir so as much of the pasta is covered by the broth as possible. Cover and seal, then set Manual or Pressure Cook for 4 minutes.
When the timer is done, allow natural release for 5 minutes, then quick release. Once the pin is down and all pressure has been released, open the lid.
Turn your IP to Sauté, and then gently stir in the cream cheese and almond milk until the cream cheese is melted. Add nutritional yeast and stir until it is well mixed in. Add the sun-dried tomatoes, salt, pepper, basil, and spinach. Stir gently until spinach is softened and ingredients are nicely mixed together.