Heat your pressure cooker by hitting the Saute function and waiting until Instant Pot reads, Hot.
Add tablespoon olive oil to inner pan of pressure cooker.
Season chicken breast cutlets generously with salt and pepper.
Sear chicken breasts 2 to 3 at a time for 1-2 minutes per side. Remove browned chicken breasts to plate.
Add in a dash more oil to inner pan of Instant Pot if no oil remains after searing chicken.
Add in a diced shallot to the Instant pot.
Add in the Marsala Wine and deglaze the pan, by scraping up any browned bits of shallot or chicken off bottom of the pan.
Add in 1 cup beef broth and the dried mushrooms.
Return browned chicken back to Instant Pot and submerge in sauce.
Place lid on the pressure cooker, turn valve to sealed and set Chicken Marsala to cook on high pressure for 5 minutes.
Once cook time has elapsed, let pressure release naturally for 5 minutes (this helps to keep the chicken from getting tough). Then release any remaining pressure.
Remove chicken breasts to serving platter.
Turn off Instant Pot and then turn back to Saute.
Whisk together cornstarch with 2 tablespoons reserved beef broth.
Whisk in a cornstarch slurry and stir constantly, until sauce is bubbly and thickened--about 3-4 minutes.
Pour sauce over chicken cutlets.