Set Instant pot to Sauté function. When the display reads HOT add the butter. Once melted add the chicken pieces.
Cook just until the chicken is no longer pink on the outside, but still pink on the inside.
Add alfredo sauce, chicken broth, garlic cloves, red pepper flakes and pasta to instant pot. Stir well to combine. Make sure to place the noodles in a criss-cross pattern so they are not clumped together and that the noodles are submerged in the liquid.
Secure the lid and set the valve to the Sealing position. Pressure Cook/Manual and for 8 minutes on HIGH pressure.
When the cooking time expires, allow pressure to naturally release for 10 minutes. Quick release any remaining pressure.
Carefully remove the lid and stir in the cheese.