Heat oven to 450°F. Line large cookie sheet with cooking parchment paper. Spray Instant Pot™ insert with cooking spray. In medium bowl, toss chicken pieces with salt and poultry seasoning. Select SAUTE; adjust to normal. Melt butter in insert. Add chicken; cook 3 to 4 minutes without moving, until browned on first side, then turn and cook 2 to 4 minutes or until chicken is browned on second side. Select CANCEL.
Stir in broth, potatoes and frozen mixed vegetables. Secure lid; set pressure valve to SEALING. Select MANUAL; cook on high pressure 2 minutes. Select CANCEL. Set pressure valve to VENTING to quick-release pressure.
In small bowl, beat cornstarch and water with whisk. Select SAUTE, and adjust to normal; heat liquid to simmering. Beat in cornstarch mixture; cook 30 to 60 seconds, beating frequently with whisk, until thickened. Select CANCEL.
Meanwhile, unroll crust on work surface. With 2 1/2-inch round cutter, cut 16 rounds from crust, rerolling once; discard scraps. Place pie crust rounds on cookie sheet. Bake 7 to 9 minutes or until golden brown and crisp. Immediately remove from cookie sheet to cooling rack.
Spoon chicken mixture into bowls. Top with pie crust rounds.